Glossary of Roofing Terms

wdt_ID Roofing Term - Definition
1 AAMA - American Architectural Manufacturers Association
2 Abrasion Resistance - the ability to resist being worn away by contact with another moving, abrasive surface, such as foot traffic, mechanical equipment, wind-blown particles, etc.
3 Absorption - the ability of a material to accept within its body, quantities of gases or liquid, such as moisture.
4 Accelerated Weathering - the exposure of a specimen to a specified test environment for a specified time with the intent of producing in a shorter time period, effects similar to actual weathering.
5 ACI - American Concrete Institute
6 Acid etch - in waterproofing, the use of a strong acid to remove the surface of concrete to expose the aggregate.
7 ACIL - American Council of Independent Laboratories
8 Acrylic coating - a liquid coating system based on an acrylic resin. Generally, a latex-based coating system that cures by air drying.
9 Acrylic resin - polymers of acrylic or methacrylic monomers. Often used as a latex base for coating systems.
10 Active metal (anodic) - a metal or material that readily gives up electrons to a cathodic (noble) material. (See anodic). An active metal will corrode in the presence of moisture when in contact with a cathodic metal.
11 Adhere - to cause two surfaces to be held together by adhesion, typically with asphalt or roofing cements in built-up roofing and with contact cements in some single-ply membranes.
12 Adhesion - steady or firm attachment.
13 Adhesive bond break - a material to facilitate independent movement between two units that would otherwise bond together.
14 AFA - American Fiberboard Association
15 AGC - Associated General Contractors of America
16 Aged R-value - thermal resistance value established by utilizing artificial conditioning procedures for a prescribed time period.
17 Aggregate—(1) Crushed stone, crushed slag, or water-worn gravel used for surfacing a built-up roof; (2) Any granular mineral material.
18 Aging - the effect on materials that are exposed to an environment for an interval of time.
19 AHA - American Hardboard Association
20 AIA - American Institute of Architects
21 Air Leakage - the unintended movement of air from a location where it is intended to be contained to another location.
22 Alligatoring - Shrinkage cracking of the surfacing bitumen on a built-up roof, producing a pattern similar to an alligator’s hide. The cracks may or may not extend through the entire surfacing bitumen thickness.
23 Aluminized Steel - sheet steel with a thin aluminum coating bonded to the surface to enhance weathering characteristics.
24 Aluminum - a nonrusting, malleable metal sometimes used for metal roofing and flashing.
25 Alloys, polymeric - A blend of two or more polymers, e.g., a rubber and a plastic to improve a given property, e.g., impact strength.
26 Ambient Temperature - the temperature of the air; air temperature.
27 Anodic - a metal or material that readily gives up electrons to a cathodic material in the presence of a electrolyte (see Galvanic series).
28 ANSI - American National Standards Institute.
29 Anticapillary hem - a hem used in a metal panel seam to reduce the potential for water migration.
30 APA - American Plywood Association
31 APC - American Plastics Council.
32 APC/SPFA - American Plastics Council/Spray Polyurethane Foam Alliance.
33 APP - see Atactic Polypropylene.
34 Application Rate - the average quantity (mass, volume, or thickness) of material applied per unit area.
35 Apron Flashing - a term used for a flashing located at the juncture of the top of the sloped roof and a vertical wall, chimney or steeper-sloped roof.
36 Architectural panel - a metal roof panel, typically a double standing seam or batten seam; usually requires solid decking underneath and relies on slope to shed water.
37 Architectural shingle - an asphalt shingle that provides a dimensional appearance.
38 Area divider - a raised, flashed assembly typically a single- or double-wood member attached to a wood base plate, that is anchored to the roof deck. It is used to accommodate thermal stresses in a roof system where an expansion joint is not required, or
39 Area practices - design or application techniques peculiar to a specific geographical region.
40 ARMA - Asphalt Roofing Manufacturers Association.
41 ASA - American Subcontractors Association
42 Asbestos - a group of natural, fibrous, impure silicate materials.
43 ASC - Associated Specialty Contractors
44 ASHI - American Society of Home Inspectors
45 ASHRAE - American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc.
46 Asphalt - a dark brown or black substance found in a natural state or, more commonly, left as a residue after evaporating or otherwise processing crude oil or petroleum. Asphalt may be further refined to conform to various roofing grade specifications: De
47 Asphalt emulsion - a mixture of asphalt particles and an emulsifying agent, such as bentonite clay and water.
48 Asphalt felt - An asphalt-saturated and/or asphalt-coated felt (see Felt).
49 Asphalt primer - see Primer.
50 Asphalt roof cement - a trowelable mixture of solvent-based bitumen, mineral stabilizers, other fibers and/or fillers. Classified by ASTM Standard D 2822-91 Asphalt Roof Cement, and D 4586-92 Asphalt Roof Cement, Asbestos-Free, Types I and II. Type I is s
51 Asphalt shingle - a shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather. (see Shingle)
52 Asphalt, air blown - An asphalt produced by blowing air through molten asphalt at an elevated temperature to raise its softening point and modify other properties.
53 Asphaltene - a high molecular weight hydrocarbon fraction precipitated from asphalt by a designated solvent (paraffinic naphtha) at a specified temperature and solvent-asphalt ratio.
54 ASTM - American Society for Testing and Materials.
55 Atactic - A chain of molecules in which the position of the side methyl groups is more or less random. (Amorphic; Low Crystallinity)
56 Atactic polypropylene - a group of high molecular weight polymers formed by the polymerization of propylene.
57 Attic - the cavity or open space above the ceiling and immediately under the roof deck of a steep-sloped roof.
58 AWPA - American Wood Preservatives Association
59 AWS - American Welding Society
60 Back-nailing (also referred to as "Blind-nailing") - the practice of blind nailing the back portion of a roofing ply, steep roofing unit, or other components in a manner so that the fasteners are covered by the next sequential ply, or course, and are not
61 Back-Surfacing - fine mineral matter applied to the back side of asphalt shingles and roll roofing to keep them from sticking together while packaged.
62 Ballast - Loose aggregate, concrete pavers, or other material designed to prevent wind uplift or flotation of a loose-laid roof system.
63 Bar joist - (see Steel joist).
64 Barrel vault - a building profile featuring a rounded profile to the roof on the short axis, but with no angle change on a cut along the long axis.
65 Barrier board - noncombustible board stock material of low thermal conductivity placed between two elements of a roof assembly.
66 Base flashing (membrane base flashing) - plies or strips of roof membrane material used to close-off and/or seal a roof at the horizontal-to-vertical intersections, such as at a roof-to-wall juncture. Membrane base flashing covers the edge of the field me
67 Base ply - the bottom or first ply in a built-up roof membrane when additional plies are to be subsequently installed.
68 Base sheet - an impregnated, saturated, or coated felt placed as the first ply in some low-slope roof systems.
69 Batten - (1) cap or cover; (2) in a metal roof, a metal closure set over, or covering the joint between, adjacent metal panels; (3) in a wood, a strip of wood usually set in or over the structural deck, used to elevate and/or attach a primary roof coverin
70 Batten seam - a metal panel profile attached to and formed around a beveled wood or metal batten.
71 Beaufort scale - A scale in which the force of the wind is indicated by numbers from 0 to 12. No.7 is “near gale” at 52-61 km/h (32-38 m.p.h.). No. 9 is “strong gale” at 76-87 km/h (47-54 m.p.h.).
72 Bentonite - a porous clay formed by the decomposition of volcanic ash that swells 5 to 6 times its original volume in the presence of water.
73 Bermuda seam - a metal panel profile featuring a step-down profile that runs perpendicular to the slope of the roof.
74 Bi-Level Drain - see Dual-Level Drain.
75 Bird bath - random, inconsequential amounts of residual water on a roof membrane.
76 Bird Screen - wire mesh used to prevent birds from entering the building through ventilators, louvers, or other openings. (See Insect Screen.)
77 Bitumen—(1) A class of amorphous, black or dark colored, (solid, semisolid, or viscous) cementitious substances natural or manufactured, composed principally of high molecular weight hydrocarbons, soluble in carbon disulfide, and found in asphalts, tars,
78 Bitumen-Stop - see Envelope and Bleed Sheet.
79 Bituminous emulsion - A suspension of minute globules of bituminous material in water or in an aqueous solution.
80 Bituminous, adj. - Containing or treated with bitumen. Examples: bituminous concrete, bituminous felts and fabrics, bituminous pavement.
81 Blackberry (also referred to as "Blueberry" or "Tar-boil") - a small bubble or blister in the flood coat of an aggregate-surfaced built-up roof membrane.
82 Blanket (batt) insulation - Fiberglass insulation in roll form, often installed between metal roof panels and the supporting purlins, or between ceiling joists.
83 Bleed-sheet - a sheet material used to prevent the migration of bitumen.
84 Bleeder strip - (see Rake-Starter).
85 Blind-nailing - the use of nails that are not exposed to the weather in the finished roofing system.
86 Blister - an enclosed pocket of air, which may be mixed with water or solvent vapor, trapped between impermeable layers of felt or membrane, or between the membrane and substrate.
87 Block or board thermal insulation - Rigid or semi-rigid thermal insulation preformed into rectangular units.
88 Blocking - sections of wood (which may be preservative treated) built into a roof assembly, usually attached above the deck and below the membrane or flashing, used to stiffen the deck around an opening, act as a stop for insulation, support a curb, or se
89 Blocking, wood - Treated wood members designed to help prevent movement of insulation.
90 Blowing agent - A compounding ingredient used to produce gas by chemical or thermal action, or both, in manufacture of hollow or cellular articles.
91 Blueberry - A small bubble or blister in the flood coating of a gravel-surfaced membrane.
92 Bodied solvent adhesive - An adhesive consisting of a solution of the membrane compound in solvent used in the seaming of membranes.
93 BOCA - Building Officials and Code Administrators, International, Inc. (author of "The BOCA National Building Code").
94 BOMA - Building Owners & Managers Association, International
95 Bond - The adhesive and cohesive forces holding two roofing components in positive contact.
96 Bond, Chemical - adhesion between surfaces, usually of similar materials, resulting from a chemical reaction or cross-linking of polymer chains.
97 Bond, Mechanical - adhesion between surfaces resulting from interfacial forces or a physical interlocking.
98 Bonding Agent - a chemical substance applied to a suitable substrate to create bond between it and a succeeding layer.
99 Boot - (1) a covering made of flexible material, which may be preformed to a particular shape, used to exclude dust, dirt, moisture, etc., from around a penetration; (2) a flexible material used to form a closure, sometimes installed at inside and outside
100 Brake - hand- or power-activated machinery used to bend metal.
101 Bridging - (1) when membrane or base flashing is unsupported at a juncture; (2) bridging in steep-slope roofing occurs when reroofing over standard-sized asphalt shingles with metric-sized asphalt shingles.
102 Breaking strain—% elongation at which a sheet or other tested component ruptures under tensile force.
103 Breaking stress - Stress (in force per linear or area units) at which sheet, or other tested component, ruptures under tensile force.
104 British thermal unit (BTU) - the heat energy required to raise the temperature of 1 pound of water one degree Fahrenheit (joule). For the metric equivalent, see Joule.
105 Broadcast - uniformly cast or distribute grandular or aggregate surfacing material.
106 Brooming - to improve the embedding of a ply or membrane by using a broom or squeegee to smooth it out and ensure contact with the adhesive under the ply or membrane.
107 Buckle - an upward, elongated displacement of a roof membrane frequently occurring over insulation or deck joints. A buckle may be an indication of movement within the roof assembly.
108 Btuh - Btu per hour.
109 Building code - Published regulations and ordinances established by a recognized agency describing design loads, procedures, and construction details for structures. Usually applying to designated political jurisdiction (city, county, state, etc.). Buildi
110 Built-up roofing (BUR) - A continuous, semi-flexible membrane consisting of multiple plies of saturated felts, coated felts, fabrics or mats assembled in place with alternate layers of bitumen, and surfaced with mineral aggregate, bituminous material, a l
111 Bull - Roofer’s term for flashing or plastic cement.
112 Bundle - an individual package of shakes or shingles.
113 Bun stock - large solid box-like structure formed during the production of polystyrene insulation; individual board stock pieces are then cut from the bun.
114 Bush Hammer - a hammer, originally a hand tool but now usually power driven, having a serrated face containing many pyramid-shaped points; used to provide a roughened surface on concrete.
115 Butt joint - a joint formed by adjacent, separate sections of material, such as where two neighboring pieces of insulation abut.
116 Button punch - a process of indenting two or more thicknesses of metal that are pressed against each other to prevent slippage between the metal.
117 Butyl - rubber-like material produced by polymerizing isobutylene.
118 Butyl coating - an elastomeric coating system derived from polymerized isobutylene. Butyl coatings are characterized by low water vapor permeability.
119 Butyl rubber - A synthetic elastomer rubber based on isobutylene and a minor amount of isoprene. It is vulcanizable and features low permeability to gases and water vapor and good resistance to aging, chemicals and weathering.
120 Butyl tape - a sealant tape sometimes used between metal roof panel seams and/or end laps; also used to seal other types of sheet metal joints, and in various sealant applications.
121 C-channel - a structural framing member.
122 CABO - Council of American Building Officials
123 Calender - (1) to press between rollers or plates in order to smooth and glaze or to thin into sheets; (2) a machine for calendering.
124 Calendering - a manufacturing process by which some polymeric membranes and other sheetings are produced.
125 Camber - a slight convexity, arching or curvature (as of a beam, roof deck or road).
126 Canopy - Any overhanging or projecting roof structure with the extreme end usually unsupported, typically over entrances or doors.
127 Cant - in SPF-based roofing, a beveling of foam at horizontal/vertical joints to increase strength and promote water run off.
128 Cant strip - A beveled strip used under flashings to modify the angle at the point where the roofing or waterproofing membrane meets any vertical element.
129 Cap flashing - (1) usually composed of metal, used to cover or shield the upper edges of the membrane base flashing wall flashing; (2) a flashing used to cover the top of various buildings components, such as parapets or columns. (See Flashing and Coping.
130 Cap sheet - a sheet, often granule-surfaced, used as the top ply of some built-up or modified bitumen roof membranes and/or flashings.
131 Capacitance meter - a device used to locate moisture or wet materials within a roof system by measuring the ratio of the change to the potential difference between two conducting elements separated by a non-conductor.
132 Capillary action - (1) the action by which the surface of a liquid where it is in contact with a solid is elevated or depressed depending on the relative attraction of the molecules of the liquid for each other and for those of the solid; (2) the siphonin
133 Catalyst - an ingredient that initiates a chemical reaction or increases the raate of a chemical reaction when combined with another chemical.
134 Cathodic - a metal or material that readily attracts electrons from an anodic material in the presence of an electrolyte (see Galvanic Series).
135 Caulk - A composition of vehicle and pigment, used at ambient temperatures for filling joints/sealing joins or junctures that remains elastic for an extended period of time after application.
136 Caulking - (1) the physical process of sealing a joint or juncture; (2) sealing and making weather-tight the joints, seams, or voids between adjacent surfaces by filling with a sealant.
137 Cavitation - the formation of a partial vacuum or cavity in a liquid.
138 Cavity Wall - an exterior wall usually of masonry, consisting of an outer and inner withe separated by a continuous air space, but connected together by wire or sheet-metal tiles.
139 CCF - 100 cubic feet.
140 Cellular glass insulation - a rigid closed-cell insulation board made from crushed glass and hydrogen sulfide gas.
141 Cementitious waterproofing - heavy cement-based compounds and various additives that are mixed and packaged for use in a dry form; the packaged mixture is then mixed with water and liquid bonding agents to a workable concrete-like consistency.
142 Centipoise - a unit of measure of absolute viscosity. (The viscosity of water is one centipoise. The lower the number, the less viscous the material.)
143 Centistoke - a unit of viscosity; the ratio of a liquid's absolute viscosity to the density of that liquid.
144 CERL - Construction Engineering Research Laboratory.
145 Chalk - a powdery residue on the surface of a material.
146 Chalk line - a line made on the roof or other flat surface by snapping a taut string or 
147 cord dusted with colored chalk.
148 Chalk resistance - A measurement of performance for paint systems; the ability to resist a dusty/chalky appearance over time.
149 Chalking - A powdery residue on the surface of a material resulting from degradation or migration of an ingredient, or both.
150 Channel flashing - in steep-slope roof construction, a type of flashing used at roof-to-wall junctures and other roof-to-vertical plan intersections where an internal gutter is needed to handle runoff. Commonly used with profile tile.
151 Chemical resistance - the ability to withstand contact with specified chemicals without a significant change in properties.
152 Chevron - a style of metal panel seaming/design.
153 Chimney - stone, masonry, prefabricated metal, or a wood framed structure, containing one or more flues, projecting through and above the roof.
154 Channel mopping - See Strip mopping under Mopping.
155 Chlorinated polyethylene (CPE) - a thermoplastic material, used for single-ply roof membranes, composed of high molecular weight polyethylene which has been chlorinated with a process that yields a flexible rubber-like material.
156 Chlorosulfonated polyethylene (CSPE or CSM) - probably best known by the DuPont trade name HypalonTM), a synthetic, rubber-like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produce a self-vu
157 Cladding - a material used as the exterior wall enclosure of a building.
158 Cleat - a continuous metal strip, or angled piece, used to secure metal components (also see Clip).
159 Clerestory - an upward extension of enclosed space created by carrying a setback vertical, wall (typically glazed) up and through the roof slope. Two intersecting shed roofs on different planes. 
160 Clip - a non-continuous metal component or angle piece used to secure two or more metal components together. (see Cleat.)
161 Clipped gable - a gable cutback near the peak in a hip-roof form.
162 Closed-cut valley - a method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches (51 mm) from the valley centerline.
163 Closure strip - A resilient strip such as neoprene, flat on one side and formed to the contour of ribbed sheets on the other, used to close openings created by joining metal sheets and flashings.
164 Coal tar bitumen - a proprietary trade name for Type III coal tar used as the damp proofing or waterproofing agent in dead-level or low-slope built-up roof membranes and membrane waterproofing systems, conforming to ASTM D 450, Type III.
165 Coefficient of thermal expansion - The change in length per unit of length for a unit change in temperature. (Thus the coefficient per 0F must be multiplied by 1.8 for the coefficient per oC.)
166 Coal tar - a dark brown to black colored, semi-solid hydrocarbon produced by the distillation of coal. Coal tar pitch is further refined to conform to the following roofing grade specifications:
167 Coal tar felt - A felt saturated or impregnated with refined coal tar.
168 Coal tar pitch - Dark brown to black, solid cementitious material obtained as residue in the partial evaporation or distillation of coal tar. A coal tar used as the waterproofing agent in dead-level or low-slope built-up roof membranes and membrane waterp
169 Coal tar roof cement - a trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers. Classified by ASTM Standard D 4022, "Coal Tar Roof Cement, Asbestos Container."
170 Coal tar waterproofing pitch - a coal tar used as the dampproofing or waterproofing agent in below-grade structures, conforming to ASTM Specification D 450, Type II.
171 Coarse orange peel surface texture - a surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is acceptable for receiving a protective coating because of the roundness of the nodules and valleys. 
172 Coated base sheet - a coated felt intended to be used as a base ply in a built-up or modified bitumen roof membrane.
173 Coated fabric - Fabrics impregnated and/or coated with a plastic like material in the form of a solution, dispersion hot melt, or powder. (The term also applies to materials resulting from the application of a preformed film to a fabric by means of calend
174 Coated sheet (or felt)—(1) An asphalt felt that has been coated on both sides with harder, more viscous asphalt; (2) A glass fiber felt that has been simultaneously impregnated and coated with asphalt on both sides.
175 Coating - a layer of liquid material applied to a surface for protection or appearance.
176 Cobwebbing - a phenomenon observed during spray application characterized by the formation of web-like threads along with the usual droplets leaving the spray gun nozzle.
177 Code - a collection of laws (regulations, ordinances or statutory requirements) adopted by governmental authority. (see Building code and Model code.)
178 Coefficient of thermal expansion - the coefficient of change in dimension of a material per unit of dimension per degree change in temperature.
179 Cohesion - the molecular forces of attraction by which the body of a material is held together.
180 Coil coating - the application of a finish to a coil of metal using a continuous mechanical coating process.
181 Cold Flow - relatively slow deformation of a material at or below room temperature. (See Creep).
182 Cold forming - the process of shaping metal into desired profiles without the application of heat.
183 Cold roof assembly - a roof assembly configured with the insulation below the deck, not typically in contact with the deck, allowing for a ventilation space. The temperature of the roof assembly remains close to the outside air temperature.
184 Cold process roofing - a continuous, semi-flexible roof membrane, consisting of a ply or plies of felts, mats or other reinforcement fabrics that are laminated together with alternate layers of liquid-applied (usually asphalt-solvent based) roof cements o
185 Collector Box - see Conductor Head.
186 Color stability - the ability of a material to retain its original color after exposure to weather.
187 Column - in structures, a relatively long, slender structural compression member such as a post, pillar or strut; usually vertical which acts in (or near) the direction of its longitudinal axis.
188 Combing ridge - a term used to describe an installation of finishing slate or wood at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.
189 Combustible - capable of burning.
190 Combustion - a chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow or flames; the process of burning.
191 Compatible materials - two or more substances that can be mixed, blended, or attached without separating, reacting, or affecting the materials adversely.
192 Composite board roof insulation - rigid board insulation generally comprised of perlite or wood fiberboard factory bonded to polyisocyanurate or polystyrene.
193 Composition shingle - a unit of asphalt shingle roofing.
194 Compounded thermoplastics - a category of roofing membranes made by blending thermoplastic resins with plasticizers, various modifiers, stabilizers, flame retardants, UV absorbers, fungicides, and other proprietary substances, alloyed with proprietary org
195 Compressive strength - the property of a material that relates to its ability to resist compression loads.
196 Concealed plate - see Cover plate.
197 Concealed-nail method - a method roofing application in which all nails are driven into the underlying course of roofing and covered by a subsequent, overlapping course.
198 Condensate - the liquid resulting from the condensation of a gas.
199 Condensation - The conversion of water vapor or other gas to liquid as the temperature drops or atmospheric pressure rises. (See also Dew Point)
200 Condense - to make denser or more compact, as when a material (e.g., water vapor) changes from its gas phase to its liquid phase.
201 Conditioning - the storage of a material specimen under specified temperature, humidity, etc. for a specified time prior to testing.
202 Conductance, thermal - The thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature difference is established between the surfaces. C=(W/ m2•K) C=(Btu/h•ft2•0F).
203 Conductivity (Thermal) - The time rate of transfer of heat by conduction through a unit thickness across unit area for unit difference of temperature.
204 Conductivity, transmission, by conduction only, in unit time through unit area between two isothermal surfaces of an infinite slab of a homogeneous material of unit thickness, in a direction perpendicular to the surface, when unit temperature difference i
205 Conductor head - an enlargement or catch basin at the top of a downspout or leader to receive rainwater from a gutter or scupper.
206 Construction joint - (1) a joint where two successive placements of concrete meet; (2) a separation provided in a building which allows its component parts to move with respect to each other.
207 Contact cements - adhesives used to adhere or bond various roofing components. These adhesives adhere mated components immediately on contact of surfaces to which the adhesive has been applied.
208 Contamination - the process of making a material or surface unclean or unsuited for its intended purpose, usually by the addition or attachment of undesirable foreign substances.
209 Control joint - a groove which is formed, sawed, or tooled in a concrete or masonry structure to regulate the location and amount of cracking and separation resulting from the dimensional change or different parts of the structure, thereby avoiding the de
210 Coping - the covering piece on top of a wall exposed to the weather, usually made of metal, masonry, or stone and sloped to carry off water.
211 Copolymer - the product of polymerization of two or more substances (as two different isomers) together.
212 Copolymerization - a chemical reaction that results in the bonding of two or more dissimilar monomers to produce large, long-chain molecules that are copolymers.
213 Copper
214 a natural weathering metal used in metal roofing or flashing; typically used in 16 ounce per square foot (0.56 mm) and 20 ounce per square foot (0.69 mm) thicknesses.
215 Core cut or core sample - (1) a sample from a low-slope roof system taken for the purpose of obtaining primarily qualitative information about its construction. Typically, core cut analysis can verify or reveal the type of membrane surfacing; the type of
216 Cornice - the decorative horizontal molding or projected roof overhang.
217 Counter batten - vertical wood strips installed on sloped roofs over which horizontal battens are secured. The primary roof covering is attached or secured to these horizontal battens.
218 Counterflashing - Formed metal or elastomeric sheeting secured on or into a wall, curb, pipe, rooftop unit, or other surface, to shield the upper edge of a base flashing and its associated fasteners.
219 Course - (1) the term used for a row of roofing material that forms the roofing, waterproofing or flashing system; (2) one layer of a series of materials applied to a surface (e.g., a five-course wall flashing is composed of three applications of roof cem
220 Cove - see Fillet.
221 Cover board - an insulation board used over closed cell plastic foam insulation (e.g., polyisocyanurate) to prevent blistering when used in conjunction with hot bituminous membranes. Suitable cover board insulation are glass-faced siliconized gypsum board
222 Cover plate - a metal strip sometimes installed over or under the joint between formed metal pieces.
223 Coverage - The surface area to be continuously covered by a specific quantity of a particular material.
224 Covering - The exterior roof and wall covering for a metal building system.
225 CPA - copolymer alloy.
226 CPE - Chlorinated Polyethylene.
227 Crack - a non-linear separation or fracture occurring in a material.
228 Cream time - time in seconds (at a given temperature) when the A and B components of polyurethane foam will begin to expand after being mixed. Recognizable as a change in color of the materials.
229 Creep - the permanent deformation of a roofing material or roof system caused by movement of the roof membrane, or compression of a roof insulation board at fastener positions, that results from continuous load or thermal stress or loading. Creep at roof
230 Cricket - A relatively small, elevated area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection. (See Saddle)
231 Cross Ventilation - the effect that is provided when air moves through a roof cavity between the vents.
232 Cross-linking - the formation of chemical bonds between polymeric chains. Cross-linking of rubber is referred to as vulcanizing or "curing."
233 CRREL - Cold Regions Research and Engineering Laboratory.
234 Crystalline waterproofing - a compound of cement, quartz or silica sand, and other active chemicals that are mixed and packaged for use in a dry powder form; the packaged mixture is then mixed with water and applied to a concrete surface where it penetrat
235 CSI - Construction Specifications Institute
236 CSM - ASTM designation for chlorosulfonated polyethylene. (See CSPE.)
237 CSPE - chlorosulfonated polyethylene.
238 Cupola - a relatively small roofed structure, generally set on the ridge or peak of a main roof area for ventilation or aesthetic purposes.
239 Curb - (1) a raised member used to support roof penetrations, such as skylights, mechanical equipment, hatches, etc. above the level of the roof surface; (2) a raised roof perimeter relatively low in height.
240 Cure - To change the properties of a polymeric system into a more stable, usable condition by the use of heat, radiation, or reaction with thermal
241 Cure time - the time required for a material to reach its desirable long-term physical characteristics.
242 Cured concrete - concrete that has attained its intended design performance properties.
243 Curing agent - an additive in a coating or adhesive that results in increased chemical activity between the components with an increase or decrease in rate of cure.
244 Curing compound - a liquid that is sprayed or otherwise applied to newly placed concrete which retards the loss of water during curing.
245 Cutback - Solvent-thinned bitumen used in cold process roofing adhesives, flashing cements, and roof coatings.
246 Cutoff - a permanent detail designed to prevent lateral water movement in an insulation system and used to isolate sections of a roofing system. (Note: A cutoff is different from a tie-in, which may be a temporary or permanent seal.) (see Tie-In.)
247 Cutout - the open portions of a strip shingle between the tabs. Sometimes referred to as a keyway.
248 Dampproofing - Treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.
249 Dead-level - Absolutely horizontal, or zero slope. (See Slope)
250 Dead loads - the weight of a structure itself, including the weight of fixtures or equipment permanently attached to it.
251 Dead level asphalt - see Asphalt.
252 Deck - a structural component of the roof of a building. The deck must be capable of safely supporting the design dead and live loads, including the weight of the roof systems, and the additional live loads required by the governing building codes and pro
253 Deflection (bowing, sagging) - (1) the deformation of a structural member as a result of loads acting on it; (2) any displacement in a body from its static position, or from an established direction or plane, as a result of forces acting on the body.
254 Degradation - a deleterious change in the chemical structure, physical properties or appearance of a material from natural or artifical exposure (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.)
255 Degree-days - a unit used in estimating the fuel consumption for a building; equal to the number of degrees that the mean temperature, for a 24-hour day, is below the "base temperature"; the base temperature is taken as 65 degrees F (18.3 C) in the U.S.A.
256 Delamination - Separation of the plies in a membrane or separation of insulation layers after lamination.
257 Depth of measurement - The maximum thickness of a roof system upon which a given moisture survey method is effective.
258 Design loads - The “live load” (i.e. super- imposed loads) that a structure is designed to resist (with appropriate safety factor) plus “dead load” (i.e., weight of permanent loads).
259 Dew point - The temperature at which water vapor starts to condense in cooling air at the existing atmospheric pressure and vapor content.
260 Dew-point temperature - the temperature at which air becomes saturated with water vapor. The temperature at which air has a relative humidity of 100%.
261 Diaphragm - a floor slab, metal wall panel, roof panel, or the like, having a sufficiently large in-plane shear stiffness and sufficient strength to transmit horizontal forces to resisting systems.
262 Diffusion - the movement of water vapor from regions of high concentration (high water vapor pressure) toward regions of lower concentration.
263 Dimensional shingle - a shingle that is textured, overlayed, or laminated and designed to produce a three-dimensional effect. (also see Laminated shingle and Architectural shingles.)
264 Dimensional stability - the degree to which a material maintains its original dimensions when subjected to changes in temperature and humidity.
265 DOE - Department of Energy.
266 Dome - a roof that is shaped like a half-circle, or a variation of one.
267 Dormer - a structure projecting from a sloping roof usually housing a window or ventilating louver.
268 Double coverage - application of asphalt, slate, or wood roofing such that the lapped portion is at least 2 inches (50 mm) wider than the exposed portion, resulting in two layers of roofing material over the deck.
269 Double Graveling - the process of applying two layers or flood coats of bitumen and aggregate to a built-up roof. Loose aggregate should be swept from the first application prior to the second coating of bitumen and aggregate. Approximately 50% of the sec
270 Double lock standing seam - in a metal roof panel or metal cap, a standing seam that uses a double overlapping interlock between two metal panels. (see Standing seam.)
271 Double pour - Doubling of flood-coat, graveling- in operation, to provide additional waterproofing integrity for a BUR membrane.
272 Downspout - a vertical pipe or conduit used to carry runoff water from a scupper, conductor head or gutter of a building to a lower roof level or to the ground or storm water runoff system.
273 Drag load - the external force (e.g., from the weight of ice and snow) applied to a steep-slope roof system component forcing the component down slope.
274 Drain - an outlet or other device used to collect and direct the flow of runoff water from a roof area.
275 Drip edge - a metal flashing or other overhanging component with an outward projecting lower edge, intended to control the direction of dripping water and help protect underlying building components. 
276 Dry bulb temperature - the temperature of air as measured by an ordinary thermometer. 
277 Dry film thickness - the thickness, expressed in mils, of an applied and cured coating or mastic. For comparison, see Wet film thickness.
278 Dry-In or Dry-In Felt - usually the underlayment or the process of applying the underlayment for steep roofing.
279 Drying time - the time required for the loss of volatile components so that the material will no longer be adversely affected by weather conditions such as dew, rain, or freezing.
280 Dual level drain - in waterproofing, an outlet or other device with provisions for drainage at both the wearing surface level and the waterproofing membrane levels used to collect and direct the flow of runoff water from a horizontal slab. 
281 Durability - the ability to withstand physical, chemical, or environmental abuse.
282 Dust Free - a surface is considered dust free when a finger can be lightly run over the surface without picking up any dirt, dust, or chalk on the finger.
283 Dynamic load - any load which is nonstatic, such as a wind load or a moving live load.
284 Eave - The line along the sidewall formed by the intersection of the planes of the roof and wall.
285 Eave height - The vertical dimension from finished floor to the eave.
286 Eaves-trough - see Gutter.
287 ECH - polyepichlorohydrin, commonly referred to as epichlorohydrin. (see Epichlorohydrin.)
288 Edge stripping - membrane flashing strips cut to specific widths used to seal/flash perimeter edge metal and the roof membrane application of felt strips cut to narrower widths than the normal felt-roll width to cover a joint between metal perimeter flash
289 Edge venting - The practice of providing regularly spaced protected openings at a roof perimeter to relieve water vapor pressure in the insulation. (It is of doubtful efficacy.)
290 Efflorescence - A deposit or encrustation of soluble salts, generally white and most commonly consisting of calcium sulfate, that may form on the surface of stone, brick, concrete, or mortar when moisture moves through and evaporates on the masonry. cause
291 EIP - ethylene interpolymer.
292 Elasticity - the property of a body that causes it to tend to return to its original shape after deformation (as stretching, compression or torsion).
293 Elastomer - A macromolecular material that returns rapidly to its approximate initial dimensions and shape after subsequent release of stress.
294 Elastomeric - the elastic, rubber-like properties of a material that will stretch when pulled and will return relatively quickly to its original shape when released.
295 Elastomeric coating - a coating that is capable of being stretched at least twice its original length (100 percent elongation) and recovering to its original dimensions.
296 Electrolyte - a liquid, most often a solution, that will conduct current.
297 Elongation - the ratio of the extension of a material to the length of the material prior to stretching.
298 Embedment—(1) the process of pressing a felt, aggregate, fabric, mat, or panel uniformly and completely into hot bitumen or adhesive to ensure intimate contact at all points; (2) the process of pressing granules into coating in the manufacture of factory
299 Embrittlement - the loss of flexibility or elasticity of a material. 
300 Emulsion - a mixture of bitumen and water, with uniform dispersion of the bitumen or water globules, usually stabilized by an emulsifying agent or system.
301 End lap - the distance of overlap where one ply, pane, or piece extends beyond the end of the immediately adjacent underlying ply, panel, or piece.
302 Envelope (Bitumen-stop) - a continuous membrane edge seal formed at the perimeter and at penetrations by folding the base sheet or ply over the plies above and securing it to the top of the membrane. The envelope prevents bitumen seepage from the edge of
303 EPDM - A synthetic elastomer based on ethylene, propylene, and a small amount of a non-conjugated diene to provide sites for vulcanization. EPDM features excellent heat, ozone and weathering resistance, and low temperature flexibility.
304 Epichlorohydrin (ECH) - a synthetic rubber including two epichlorohydrin based elastomers. It is similar to and compatible with EPDM. 
305 Epoxy - a class of synthetic, thermosetting resins that produce tough, hard, chemical-resistant coatings and adhesives.
306 Equilibrium moisture content (EMC) - (1) the moisture content of a material stabilized at a given temperature and relative humidity, expressed as percent moisture by weight.
307 Equiviscous temperature (EVT) - application range
308 the recommended bitumen application temperature range. The range is approximately 25 degrees F (14 degrees C) above or below the EVT, thus giving a range of approximately 50 degrees F (28 degrees C). The EVT range temperature is measured in the mop cart o
309 Equiviscous temperature (EVT) for asphalt - the recommended EVT for roofing asphalt (ASTM D 312, Type I, II, III, or IV) is as follows Mop Application: the temperature at which the asphalt's apparent viscosity is 125 centipoise (0.125 Pa s). Mechanical Sp
310 Equiviscous temperature (EVT) for coal tar - the recommended EVT for roofing coal tar (ASTM D 450, Type I or III) is the temperature at which the coal tar's apparent viscosity is 25 centipoise (0.025 Pa s).
311 Ethylene interpolymers (EIP) - a group of thermoplastic compounds generally based on PVC polymers from which certain single-ply roofing membranes can be formulated.
312 Ethylene propylene diene terpolymer (EPDM) - designated nomenclature of ASTM for a terpolymer of ethylene, propylene, and a diene. EPDM material is a thermosetting synthetic elastomer.
313 EVT - Equiviscous temperature.
314 Exhaust ventilation - air that is vented or exhausted from the roof cavity, typically through vents installed on the up slope portion of the roof. For example, with most steep-slope roof assemblies, exhaust vents are typically located at or near the ridge
315 Exotherm - Heat generated in a chemical reaction.
316 Expansion cleat - a cleat designed to accommodate thermal movement of the metal roof panels.
317 Expansion joint - A structural separation between two building elements that allows free movement (expansion or contraction) between elements without damage to the roofing or waterproofing system.
318 Exposure—(1) (1) the traverse dimension of a roofing element or component not overlapped by an adjacent element or component in a roof covering. For example, the exposure of any ply in a built-up roof membrane may be computed by dividing the felt width, m
319 Extrusion - a process in which heated or unheated material is forced through a shaping orifice (a die) in one continuously formed shape, as in film, sheet, rod or tubing.
320 Eyebrow - a dormer, usually of small size, whose roof line over the upright face is typically an arched curve, turning into a reverse curve to meet the horizontal at either end. Also, a small shed roof projecting from the gable end of the larger, main roo
321 Fabric - a woven cloth or material of organic or inorganic filaments, threads, or yarns used for reinforcement in certain membranes and flashings.
322 Fabric reinforcement - A fabric, scrim, etc., used to add structural strength to a 2 or more ply polymeric sheet. Such sheeting is referred to as “supported”.
323 Fabrication—(1) The manufacturing process performed in a plant to convert raw material into finished metal building components. The main operations are cold-forming, cutting, punching, welding, cleaning, and painting; (2) the creation of large panels of r
324 Factory Mutual Research (FMR) - commonly referred to as "FM," a research and testing organization that classifies roofing components and assemblies for their fire, traffic, impact (hail), weathering, and wind-uplift resistance for four major insurance com
325 Factory seam - a splice/seam made by the manufacturer during the assembly of sections of materials into larger sheets/panels.
326 Fading - any lightening of initial color.
327 Fallback - a reduction in the softening point, sometimes caused by refluxing or overheating in a relatively closed container. (see Softening Point Drift.)
328 Fascia - (1) in steep-slope roofing, a board that is nailed to the ends of a roof rafter; sometimes supports a gutter; (2) in a low-slope roofing, the vertical or steeply sloped roof or trim located at the perimeter of a building. Typically, it is a borde
329 Fastener - any of a wide variety of mechanical securement devices and assemblies, including nails, staples, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly.
330 Feathering strips - tapered wood filler strips placed along the butt ends of old wood shingles to create a relatively smooth surface when reroofing over existing wood shingle roofs. Referred to in some regions of the country as "horse feathers" or levelin
331 Felt machine (Felt Layer) - a mechanical device used for applying bitumen and roofing felt or ply sheet simultaneously.
332 Felt - A flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture, and heat, without spinning, weaving, or knitting. Roofing felts are manufactured from vegetable fibers (organic felts), glass fibers (gl
333 Ferrule - a metal sleeve placed inside a gutter at the top. A spike or screw is nailed/screwed through the gutter face and ferrule into the fascia board to hold the gutter in place. The ferrule acts as a spacer in the gutter to maintain its original shape
334 Fiberglass Insulation - blanket or rigid board insulation, composed of glass fibers bound together with a binder, faced or unfaced, used to insulate roofs and walls. Rigid boards usually have an asphalt and kraft paper facer.
335 Field of the Roof - the central or main portion of a roof, excluding the perimeter and flashing.
336 Field seam - a splice or seam made in the field (not factory) where overlapping sheets are joined together using an adhesive, splicing tape, or heat- or solvent-welding.
337 Filler - a relatively inert ingredient added to modify physical characteristics.
338 Fillet - a heavy bead of waterproofing compound or sealant material generally installed at the point where vertical and horizontal surfaces meet; the desired effect to take out the 90 degree angle at the base of a vertical flashing.
339 Film - sheeting having a nominal thickness not greater than 10 mils (0.25 mm).
340 Film thickness - the thickness of a membrane or coating. Wet film thickness is the thickness of a coating as applied; dry film thickness is the thickness after curing. Film thickness is usually expressed in mils (thousandths of an inch).
341 Fin - a term used to describe a deck surface condition. A sharp raised edge (generally in concrete) capable of damaging a roof membrane or vapor retarder.
342 Fine mineral surfacing - water-insoluble, inorganic material, more than 50 percent of which passes through a No. 35 sieve. Used on the surface of various roofing materials and membranes to prevent sticking.
343 Fire resistance - the property of a material or assembly to withstand fire or give protection from it.
344 Fire retardant treated (FRT) plywood - plywood which has been impregnated, under pressure, with mineral salts; in the event of fire, the burning wood and salts emit noncombustible gases and water vapor instead of the usual flammable vapors.
345 Fishmouth-(also referred to as an edge wrinkle) (1) a half-cylindrical or half-conical shaped opening or void in a lapped edge or seam, usually caused by wrinkling or shifting of ply sheets during installation; (2) in shingles, a half-conical opening form
346 Flaking - in protective coatings, the detachment of small pieces of the coating film.
347 Flame retardant - a chemical used to impart flame resistance.
348 Flame spread - a propagation of a flame away from its source of ignition.
349 Flammability - those characteristics of a material that pertain to its relative ease of ignition and ability to sustain combustion.
350 Flange - the projecting edge of a rigid or semi-rigid component, such as a metal edge flashing flange.
351 Flash point - the lowest temperature at which vapors above a volatile combustible substance ignite in air when exposed to a flame.
352 Flashing - components used to weatherproof or seal the roof system edges at perimeters, penetrations, walls, expansion joints, valley, drains, and other places where the roof covering is interrupted or terminated. For example, membrane base flashing cover
353 Flashing cement - a trowelable mixture of solvent-based bitumen and mineral stabilizers that may include asbestos or other inorganic or organic fibers. Generally, flashing cement is characterized as vertical-grade, which indicate it is intended for use on
354 Flashing collar - (sometimes referred to as a roof jack or flashing boot) an accessory flashing used to cover and/or seal soil pipe vents and other penetrations through the roof.
355 Flash point - Temperature at which a test flame ignites vapor above a liquid surface.
356 Flat asphalt - A roofing asphalt conforming to the requirements of Specification D312, Type II.
357 Flat lock - a method of interlocking metal panels in which one panel edge is folded back on top of itself and the other panel is folded under, after which the two panels are hooked together.
358 Fleece - mats or felts composed of fibers, sometimes used as a membrane backer.
359 Flood (pour) coat - the surfacing layer of bitumen into which surfacing aggregate is embedded on an aggregate-surfaced built-up roof. 
360 Flood test - the procedure where a controlled amount of water is temporarily retained over a horizontal surface to determine the effectiveness of the waterproofing system.
361 Fluid-applied elastomer - An elastomeric material, fluid at ambient temperature, that dries or cures after application to form a continuous membrane. Such systems normally do not incorporate reinforcement.
362 Fly-in - method of application for roll materials by which the dry sheet is set into the bitumen or adhesive applied to the roof surface.
363 FM - see Factory Mutual Research (FMR).
364 Foam stop - the roof edge treatment upon which SPF is terminated.
365 Force - a strength or energy exerted or brought to bear; cause of motion or change.
366 FPL - Forest Products Laboratory.
367 Framed Opening - an opening in a wall or roof of a building, surrounded by structural framing, usually for field installed accessories such as skylights or ventilators.
368 Froth pack - a term used to describe small, disposable aerosol cans that contain SPF components. Two component froth packs are available to do small repairs for sprayed polyurethane foam-based roofs.
369 Friability - The tendency of a material or product to crumble or break into small pieces easily.
370 G-90 - a designation for galvanized metal sheet, indicating 0.90 ounces (26 g) of zinc per square foot, measured on both sides.
371 Gable roof - A single-ridged roof that terminates in gable end(s).
372 Galvalume - trade name for a metal alloy coating that is composed of aluminum, zinc and silicone.
373 Galvanic action - an electrochemical action that generates electrical current between two metals of dissimilar electrode potential.
374 Galvanic series - an list of metals and alloys arranged according to their relative electrolytic potentials in a given environment.
375 Galvanize - to coat steel or iorn with zinc.
376 Galvanized steel - Steel coated with zinc for corrosion resistance.
377 Gambrel - a roof that has two pitches on each side, where the upper roof area has less slope than the lower roof areas.
378 Gauge - a metal thickness measurement.
379 Geocomposite - a prefabricated water drainage material used to relieve hydrostatic pressure against waterproofing and promote drainage.
380 Geodesic Dome - a rounded structure made of short, straight, triangular sections that form polygons. 
381 Geotextile - a tightly woven fabric used to restrict the flow of fine soil particles and other contaminants while allowing water to pass freely through; used to protect drainage systems from clogging.
382 Girt - a horizontal beam that supports wall cladding between columns.
383 Glass felt - Glass fibers bonded into a sheet with resin and suitable for impregnation in the manufacture of bituminous waterproofing, roofing membranes, and shingles.
384 Glass fiber insulation - blanket or rigid board insulation, composed of glass fibers bound together with a binder, faced or unfaced, used to insulate roofs and walls.
385 Glass mat - A thin mat of glass fibers with or without a binder.
386 Glass transition - The reversible change in an amorphous polymer or in amorphous regions of a partially crystalline polymer from (or to) a viscous or rubbery condition to (or from) a hard and relatively brittle one.
387 Glaze coat—(1) The top layer of asphalt in a smooth surfaced built-up roof assembly; (2) A thin protective coating of bitumen applied to the lower plies or top ply of a built-up membrane, when application of additional felts, or the flood coat and aggrega
388 Gloss - the shine, sheen, or luster of a dried film.
389 Grain - a unit used to measure in the English System of units; 7,000 grains equals 1 lb.; used as a measure of the weight of moisture in air.
390 Granule - (also referred to as mineral or ceramic granule) opaque, natural, or synthetically colored aggregate commonly used to surface cap sheets, shingles, and other granule-surfaced roof coverings.
391 Gravel - Coarse, granular aggregate, with pieces larger than sand grains, resulting from the natural erosion of rock.
392 Gravel stop - Flanged device, usually metallic, designed to prevent loose aggregate from washing off the roof and to provide a continuous finished edge for the roofing.
393 Groundwater level - at a particular site, the level below which the subsoil and rock masses of the earth are fully saturated with water.
394 Green building technology - Utilizing technology to reduce impact on the earth. Includes recyclability, reduction in carbon dioxide, ozone or other atmospheric pollutants, and reduction of urban heat islands.
395 Grout (Non-Shrink) - a cementitious material used to fill pitch-pans/pockets, prior to the application of a pourable sealer.
396 Gusset - used at the bottom of a steep-slope roof system valley, a large flat metal piece(s) wider than the valley to help prevent build-up at the base of the valley, either from debris or ice dam formations.
397 Gutter - a channeled component installed along the downslope perimeter of a roof to convey runoff water from the roof to the drain leaders or downspouts.
398 Gypsum board panels - cementititious board stock with noncombustible core primarily comprised of gypsum that is commonly used as a barrier board thermal barrier or cover board in a roof assembly.
399 Hand-tabbing - method of spot applying asphalt-based adhesive to shingles for securement and wind resistance.
400 Hardness - the relative resistance of a material to indentation.
401 Header - A horizontal framing structural member of a door, window, or other framed opening.
402 Headlap - the distance of overlap measured from the uppermost ply or course to the point where it laps over the undermost ply or course.
403 Heat Aging - controlled exposure of materials to elevated temperatures over time.
404 Heat flow - the quantity of heat transferred to or from a system in a unit of time.
405 Heat seaming - the process of joining thermoplastic films, membranes, or sheets by heating and then applying pressure to bring both materials in contact with each other. (see Heat welding.)
406 Heat transfer - The transmission of thermal energy from a location of higher temperature to a location of lower temperature. This can occur by conduction, convection or radiation.
407 Heat welding - method of melting and fusing together the overlapping edges of separate sheets or sections of polymer modified bitumen, thermoplastics or some uncured thermoset roofing membranes by the application of heat (in the form of hot air or open fl
408 Hem - the edge created by folding metal back on itself.
409 Hip - the inclined external angle formed by the intersection of two sloping roof planes. 
410 Hip roof - A roof which rises by inclined planes from all four sides on the building. The line where two adjacent sloping sides of a roof meet is called the Hip.
411 Hoist - a mechanical lifting device.
412 Holiday - An area where a liquid applied material is missing, a void.
413 Honeycomb - voids left in concrete resulting from failure of the mortar to effectively fill the spaces among course aggregate particles.
414 Hot-dip metallic coating - Adherent protective coating applied by immersing steel in a molten bath of coating material.
415 Hood - Cover, usually light gage metal, over piping or other rooftop equipment.
416 “Hot stuff” or “hot” - A roofer’s term for hot bitumen.
417 Hue - the subjective perception of color such as red, yellow, green, blue, purple or some combination; white, black or gray possess no hue.
418 Humidity - The amount of moisture contained in the atmosphere. Generally expressed percent relative humidity. (The ratio of the vapor pressure to the saturation pressure for given conditions times 100.)
419 Humidity test - A test involving exposure of specimens at controlled levels of humidity and temperature.
420 HVAC - heating, ventilating, and air conditioning equipment.
421 Hybrid roof covering - combination of two or more separate and distinct roof membranes; e.g., three ply smooth BUR and a modified bitumen cap.
422 Hydration - the chemical reaction by which a substance (such as Portland cement) combines with water, giving off heat to form a crystalline structure in its setting and hardening.
423 Hydrocarbons - An organic chemical compound containing mainly the elements carbon and hydrogen. Aliphatic hydrocarbons are straight chain compounds of carbon and hydrogen. Aromatic hydrocarbons are carbon-hydrogen compounds based on the cyclic or benzene
424 Hydrostatic pressure relief system - a system of perimeter and/or under slab drains used to regulate the hydrostatic pressure in the earth surrounding a below-grade structure.
425 Hydrostatic pressure - the pressure equivalent to that exerted on a surface by a column of water of a given height.
426 Hygroscopic - attracting, absorbing and retaining atmosphere moisture.
427 HypalonTM - a registered trademark of E.I. duPont de Nemours & Co., for "chlorosulfonated polyethylene" (CSPE). (see Chlorosulfonated polyethylene.)
428 ICBO - International Conference of Building Officials. 
429 Ice dam - a mass of ice formed at the transition from a warm to a cold roof surface, frequently formed by refreezing melt-water at the overhang of a steep roof, causing ice and water to back up under roofing materials.
430 Ice dam protection membrane - a continuous membrane installed under steep slope roofing materials in areas subject to ice damming that prohibits water which gets through the roof covering from getting into the structure. Must also seal the fasteners that
431 Ignition temperature - the lowest temperature at which combustion will occur spontaneously under specific conditions.
432 Impact resistance - resistance to fracture under the sudden application of an exerted force.
433 Impregnate - in roofing materials manufacture, to completely surround the fibers in a felt or mat with bitumen, with the spaces between the fibers partially or completely filled without a continuous coating of bitumen on the surface.
434 In-service R-value - thermal resistance value established under installed conditions and measured over the expected service life of the material.
435 Incline - The slope of a roof expressed in percent or in the number of vertical units of rise per horizontal unit of run. (See Slope)
436 Infrared thermography - the process of displaying variations of apparent temperatures (variation of temperature or emissivity or both) over the surface of an object by measuring variations in infrared radiance.
437 Inorganic, adj - being or composed of materials other than hydrocarbons and their derivatives, or matter that is not of plant or animal origin.
438 Insect screen - wire mesh used to prevent insects from entering the building through ventilators, louvers, or other openings.
439 Insulation
440 any of a variety of materials designed to reduce the flow of heat, either from or into a building. (see also Thermal insulation.)
441 Internal pressure - Pressure inside a building, a function of wind velocity, building height, and number and location of openings.
442 lsocyanate - A highly reactive chemical grouping composed of a nitrogen atom bonded to a carbon atom bonded to an oxygen atom; =N=C=O; a chemical compound, usually organic, containing one or more isocyanate groups.
443 Isoboard - Abridgement of polyisocyanurate foam insulation board.
444 Joist — Any of the small timbers or metal beams arranged parallel from wall to wall to support a floor, ceiling or roof of a building.
445 Joist - any of the small timbers, metal or wood beams arranged parallel to each other and spanning from wall to wall to support a floor, ceiling, or roof of a building.
446 Joule - a unit of energy or work; equals the work done by a force of 1 newton which acts over a distance of 1 meter in the direction of the force.
447 k or k-Value - thermal conductivity; the time rate of heat flow through a unit area of a homogeneous material in a direction perpendicular to isothermal planes induced by a unit temperature gradient. In English (inch-pound) units of measurement, it is the
448 k-factor - thermal conductivity for a unit thickness of material. Expressed at BtuòIn/HròFt2ò_F. R-value is equal to the thickness of the thermal material divided by the k-factor (R=x/k where x = thickness).
449 Kerf - (1) a slit or notch made by a saw or cutting torch; (2) the width of a cut made by a saw or cutting torch.
450 Kesternich test - simulates acid rain conditions by subjecting test specimens to a sulfur dioxide atmosphere as well as condensing moisture for the purpose of evaluating rust/corrosion characteristics.
451 Knee cap - a metal cover trim that fits over a panel rib after it has been cut and bent.
452 Knuckle - a metal closure, either shop-or pre-fabricated, installed over the cut seam of a continuous metal roof panel at the transition from a steep-slope roof to a vertical roof or wall.
453 Kick-out (Elbow)—(Turn-Out) A lower downspout section used to direct water away from a wall.
454 Laitance - a weak layer of cement and aggregate fines on a concrete surface that is usually caused by an overwet mixture, overworking the mixture, improper or excessive finishing or combination thereof.
455 Laminate - to join layers of materials together using fusion; the process of joining layers of materials together using adhesion.
456 Laminated shingles - see Dimensional shingles or Architectural shingles.
457 Lap - that part of a roofing, waterproofing, or flashing component that overlaps or covers any portion of the same or another type of adjacent component.
458 Lap cement - an asphalt-based roof cement formulated to adhere overlapping plies or asphalt roll roofing.
459 Lapped joint - A joint made by placing one surface to be joined partly over another surface and bonding the overlapping portions.
460 Latex - a stable dispersion of polymeric substance in an essentially aqueous medium.
461 Layer (Plywood) - A layer is a single veneer ply or two or more plies laminated with parallel grain
462 Lead - a soft malleable, heavy metal; has low melting point and a high coefficient of thermal expansion.
463 Leader head - see Conductor head.
464 Leeward - the opposite direction from which the wind is blowing. The side sheltered from the wind.
465 Life Cycling Costing - a method of economic analysis that takes into account expected costs over the useful life of an asset.
466 Lift - the sprayed polyurethane foam that results from a pass. It usually is associated with a certain pass thickness and has a bottom layer, center mass and top skin in its makeup.
467 Live load - Live load means all loads including snow, exerted on a roof except dead, wind, and lateral loads.
468 Loose-laid membrane - A un-adhered roofing membrane anchored to the substrate only at the edges and penetrations through the roof and ballasted against wind uplift by loose aggregate or payers.
469 Mansard - a decorative steep-sloped roof on the perimeter of a building.
470 Mansard roof - a steeper roof that terminates into a flat roof at its high point.
471 Masonry - construction, usually set in mortar, of natural building stone or manufactured units, such as brick, concrete block, adobe, glass block, tile, manufactured stone or gypsum block.
472 Mastic - a thick adhesive material used as a cementing agent for holding waterproofing membrane in place. (see Asphalt roof cement).
473 Mat - a thin layer of woven, non-woven, or knitted fiber that serves as reinforcement to the material or membrane.
474 Mat slab - a concrete slab designed with reinforcement to resist the uplift forces created by hydrostatic pressure.
475 Material safety data sheets (MSDS) - a written description of the chemicals in a product and other pertinent data including such things as safe handling and emergency procedures. In accordance with OSHA regulations, it is the manufacturer's responsibility
476 MBDA - formerly Metal Builders Dealers Association, now Systems Builders Association.
477 MBMA - Metal Building Manufacturers Association
478 MCA - Metal Construction Association
479 Mechanical damage - in SPF-based roofing, physical damage to a completed SPF-based roof system not caused by normal wear and tear.
480 Mechanically-fastened membranes - generally used to describe membranes that have been attached at defined intervals to the substrate.
481 Membrane - A flexible or semi-flexible roof covering or waterproofing whose primary function is the exclusion of water.
482 Memory - Tendency of a material to regain a previous configuration—notably, the tendency of glass-fiber felts not to lie flat on their substrate after unrolling; the retraction of single-ply roll goods which were stretched during production or winding.
483 Metal - any of various opaque, fusible, ductile and typically lustrous substances that are good conductors of electricity and heat.
484 Metal Flashing - accessory components fabricated from sheet metal and used to weatherproof terminating roof covering edges. Frequently used as through-wall flashing, cap flashing (coping), counterflashing, step-flashing, etc. (See Flashing.)
485 Metal Film - a layer of foil made from a single metallic substance, or from an alloy, that is laminated to a membrane during manufacture. The metal foil serves as the weathering surface of the membrane or flashing material.
486 Metal rain collar - a metal counterflashing used to wrap a penetration and prevent water infiltration though the top of the penetration base flashing.
487 Metal roof panel - an interlocking metal sheet having a minimum installed weather exposure of 3 square feet (279000 mm2 or 0.28 m2)per sheet.
488 Metal roof shingle - an interlocking metal sheet having an installed weather exposure less than 3 square feet (279000 mm2 or 0.28 m2) per sheet.
489 Metallic waterproofing - consist of finely graded iron particles combined with an oxidizing catalyst. When mixed with water (or water, cement, and sand), the finely distributed particles expand, creating a waterproof layer that becomes a part of the surfa
490 Meter - unit of length measurement in the metric system, 1 meter is equal to 39.37 inches.
491 Mica Dust - crystallized complex silicate minerals that are pulverized into dust form for use as a release agent. (See Talc.)
492 Microbiological Resistance - the ability of a material to resist attack and degradation by various air- and soil-borne micro-organisms.
493 Migration - the absorption of oil or vehicle from a compound into an adjacent porous surface.
494 Mil - a unit of measure, one mil is equal to 0.001 inches, or 25.4 micrometers (um), often used to indicate the thickness of a roofing membrane.
495 Mildew - a superficial growth produced on organic matter or living plants by fungi.
496 Millimeter - a unit of measure equal to one thousandth (0.001) of a meter, or 0.03937 inches.
497 MIMA - Mineral Insulation Manufacturers Association
498 Mineral fiber - insulation composed principally of fibers manufactured from rock, slag or glass, with or without binders.
499 Mineral Granules - Natural or synthetic aggregate, ranging in size from 500?m (1?m 10-6m) to 1/4 in. diameter, used to surface BUR or modified bitumen cap sheets, asphalt shingles, and some cold process membranes.
500 Mineral stabilizer - a fine, water-insoluble inorganic material, used in a mixture with solid or semi-solid bituminous materials.
501 Mineral-surfaced roofing - roofing materials whose surface or top layer consists of granule-surfaced sheet.
502 Mineral-surfaced sheet - a roofing sheet that is coated on one or both sides with asphalt and surfaced with mineral granules.
503 Miter - the joint produced by joining two diagonally cut pieces.
504 Miter joint - a joint between two members at an angle to each other; each member is cut at an angle equal to half the angle of the junction; usually the members are at right angles to each other.
505 Model (building) codes - a compilation of standards or codes established to provide uniformly in regulations pertaining to building construction.
506 Model Codes - Codes established to provide uniformity in regulations pertaining to building construction. Examples: Uniform Building Code published by lCBO National Building Code by BOCA Standard Building Code by SBCCI International Building Code (New)
507 Modified bitumen - (1) a bitumen modified by including one or more polymers (e.g., atactic polypropylene, styrene butadiene styrene, etc.); (2) composite sheets consisting of a polymer modified bitumen often reinforced with various types of mats or films
508 Moisture conduction - Migration by wicking as contrasted to vapor movement.
509 Moisture contour map—A map with lines connecting continuous levels of moisture. When drawn by computer the wettest areas are often indicated by darkest symbols and the driest areas left blank.
510 Moisture contour map - a map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed.
511 Moisture relief vent - a venting device installed through the roofing membrane to relieve moisture vapor pressure from within the roofing system.
512 Moisture scan - the use of a mechanical device (capacitance, infrared, or nuclear) to detect the presence of moisture within a roof assembly. (see Non-destructive testing.)
513 Mole run - A meandering ridge in a membrane not associated with insulation or deck joints.
514 Monolithic - formed from or composed of a single material; seamless.
515 Monomer - A simple molecule, which is capable of combining with a number of like or unlike molecules to form a polymer.
516 Mop-and-flop - A application procedure in which roof components (insulation boards, felt plies, cap sheets, etc.), are initially placed upside down adjacent to their ultimate locations, are coated with adhesive, and are then turned over and adhered to the
517 Mopping - Application of hot bitumen with a mop or mechanical applicator to the substrate or to the plies of a built-up or modified-bitumen roof. There are four types of mopping: (1) solid—a continuous coating; (2) spot—bitumen is applied in roughly circu
518 Mud cracking - surface cracking resembling a dried mud flat.
519 Mud slab - a layer of concrete, typically 2 inches (50 mm) to 6 inches (150 mm) thick, used as the substrate for membrane waterproofing.
520 Multiple Coat - two or more layers of coating applied to a substrate.
521 NAHB - National Association of Home Builders
522 Nail-type concrete anchor - A hammer-driven fastener with spiral or annular rings that provides pullout strength.
523 Nailer - (sometimes referred to as blocking) a piece or pieces of dimensional lumber and/or plywood secured to the structural deck or walls, which provide a receiving medium for the fasteners used to attach membrane or flashing.
524 Nailing - the application of nails. May be (1) exposed nailing of roofing wherein nail heads are exposed to the weather; (2) concealed nailing of roofing wherein nail heads are concealed from the weather by an overlapping material.
525 NBP - acrylonitrile butadiene polymer blend. One proprietary NBP membrane is commonly referred to as nitrile butadiene copolymer.
526 Needle Punched Fabric - a fabric where barbed needles (in multiple punches) achieve mechanical bonding/locking or carding of fibers.
527 Negative side waterproofing - an application wherein the waterproofing system and source of hydrostatic pressure are on opposite sides of the structural element.
528 Neoprene - Synthetic rubber (polychloroprene) used in liquid or sheet-applied elastomeric roofing membranes or flashing.
529 Nesting - (1) the installation of new metal roof deck directly on top of existing metal roof deck; (2) a method of reroofing with new asphalt shingles over existing shingles in which the top edge of the new shingle is butted against the bottom edge of the
530 Net free vent area - the area (measured in square inches) open to unrestricted air flow and commonly used as a yardstick to measure relative vent performance; the area of the opening of a vent minus the area displaced by the screening material.
531 Newton (N) - SI unit of measure for force.
532 NICA - National Insulation Contractors Association
533 Night seal (or night tie-in) - a material and/or method used to temporarily seal a membrane edge during construction to protect the roofing assembly in place from water penetration. Usually removed when roofing application is resumed.
534 Ninety-Pound - a prepared organic felt roll roofing with a granule surfacing that has a mass of approximately 90 pounds per 100 square feet, (4400 g/m²).
535 NIST - National Institute of Standards and Technology
536 Nitrile alloy - an elastomeric material of synthetic non-vulcanizing polymers.
537 Nitrile rubber - A family of copolymers of butadiene and acrylonitrile that can be vulcanized into tough oil resistant compounds. Blends with PVC are used where ozone and weathering are important requirements in addition to its inherent oil and fuel resis
538 No-cutout shingles - shingles consisting of a single solid strip with no cutouts.
539 Noble - in reference to metal, inert; opposite of active.
540 Noble metal - a metal that readily receives electrons from an anodic metal (see Galvanic series).
541 Non-Breathing Membrane - a membrane that does not allow significant amounts of water vapor or air to pass through; which has a perm rating 1.0 or less per ASTM E 96, Procedure E.
542 Non-traffic bearing - for waterproofing purposes, a membrane system requiring some form of protection barrier and wearing surface.
543 Non-Vulcanized Membrane - a membrane manufactured from thermoplastic compounds that retains its thermoplastic properties throughout the service life of the membrane.
544 Non-destructive testing (NDT) - a method to evaluate the disposition, strength or composition of materials or systems without damaging the object under test. Typically used to evaluate moisture content in roofing assemblies, the three common test methods
545 Nonflammable - not easily ignited and not burning rapidly if ignited.
546 Non-friable - a material that, when dry, cannot be crumbled, pulverized or reduced to powder by hand pressure.
547 Nonoxidizing - a material which resists oxidation in exterior exposures or accelerated weathering.
548 Nonvolatile content - the portion of a coating that does not evaporate during drying or curing under specified conditions, comprising the binder and, if present, the pigment. (The percent volatile content is obtained by subtracting the nonvolatile content
549 Nonwoven - a term used to describe the random arrangement of reinforcing fibers (glass, polyester, etc.) in a mat or scrim.
550 Nonwoven fabric - a textile structure produced by bonding or interlocking of fibers, or both, accomplished by mechanical, chemical, thermal, or solvent means and combinations thereof.
551 NRCA - National Roofing Contractors Association.
552 NTRMA - National Tile Roofing Manufacturers Association
553 Nuclear hydrogen detection (NHD) meter - a device that contains a radioactive source to emit high velocity neutrons into a roof system. Reflecting neutrons are measured by a gauge that is used to detect hydrogen; the quantity of hydrogen detected may be l
554 Nuclear Testing (Nuclear Back-Scatter) - a device that contains a radioactive source to emit high velocity neutrons into a roof system. Reflecting neutrons are measured by a gauge that is used to detect moisture.
555 Nylon - generic name for a family of polyamide polymers, used as a scrim in some fabric-reinforced sheeting.
556 Off-ratio foam - SPF which has excess isocyanate or resin. Off-ratio will not exhibit the full physical properties of normal SPF.
557 Olefin - An unsaturated open-chain hydrocarbon containing at least one double bond: ethylene or propylene.
558 Olefin plastics - Plastics based on polymers made by the polymerization of olefins or copolymerization of olefins with other monomers, the olefins being at least 50 mass %.
559 Open valley - a method of valley construction in which the steep-slope roofing on both sides are trimmed along each side of the valley, exposing the valley flashing.
560 Open time - the period of time after an adhesive has been applied and allowed to dry, during which an effective bond can be achieved by joining the two surfaces.
561 Organic, adj. - Composed of hydrocarbons or their derivatives, or matter of plant or animal origin.
562 Organic coating - Coatings that are generally inert or inhibited. May be temporary (e.g., slushing oils) or permanent (paints, varnishes, enamels, etc.).
563 Organic felt - an asphalt roofing base material manufactured from cellulose fibers.
564 Organic shingle - an asphalt shingle reinforced with material manufactured from cellulose fibers.
565 ORNL - Oak Ridge National Laboratory.
566 Osmosis - movement of a solvent through a semipermeable membrane into a solution of higher solute concentration that tends to equalize the concentration of solute on the two sides of the membranes.
567 Overflow drainage - component in a roof drainage system used to protect the roof against damage from a water load imposed by blocked or partially blocked primary drainage system; e.g., overflow scupper, overflow interior drain.
568 Overspray surface texture - in SPF roofing, a condition of the foam in which the surface shows a linear coarse textured pattern and/or a pebbled surface. This surface is generally downwind of the sprayed polyurethane path and, if severe, unacceptable for
569 Overspray - undesirable depositions of airborne spray.
570 Pallet - a platform (typically wooden) used for storing and shipping materials.
571 Pan - the bottom flat part of a roofing panel which is between the ribs of the panel.
572 Pan former - power roll-forming equipment that produces a metal roofing panel from a flat sheet.
573 Parapet wall - the part of a perimeter wall that extends above the roof.
574 Parge - in masonry construction, a coat of cement mortar on the face of rough masonry, the earth side of foundation and basement walls, or the like.
575 Partially attached - a roofing assembly in which the membrane has been "spot affixed" to a substrate, usually with an adhesive or a mechanical device.
576 Parting agent - a material applied to one or both surfaces of a sheet to prevent blocking.
577 Pascal (N/m²) - SI unit of measure for force per unit area.
578 Pass - 1) a layer of material, usually applied by the spray method, that is allowed to reach cure before another layer ("pass") is applied; 2) a term used to explain a spray motion of the foam gun in the application of the spray polyurethane foam (SPF) ma
579 Pass line - the junction of two passes of SPF. A distinct line is formed by the top skin of the bottom pass and the next pass adhering to this skin.
580 Pea gravel - Small gravel with a diameter approaching that of a pea. Size roughly defined by ASTM D448, Number 7 or smaller.
581 Peak - The uppermost point of a gable.
582 Pedestal - a support or base for roof top components such as pavers, pipes and small roof top units.
583 Peel strength - the average load per unit width required to separate progressively a flexible member from a rigid member or another flexible member.
584 Penetration-(1) any construction (e.g., pipes, conduits, HVAC supports) passing through the roof; (2) the consistency of a bituminous material expressed as the distance, in tenths of a millimeter (0.1 mm), that a standard needle penetrates vertically into
585 Percent Elongation - in tensile testing, the increase in the gauge length of a specimen measured at or after fracture of the specimen within the gauge length. Usually expressed as a percentage of the original gauge length.
586 Perlite - An aggregate used in lightweight insulating concrete and in preformed perlite insulating board, formed by heating and expanding siliceous volcanic glass.
587 Perm—(vapor transmission) Unit to measure water vapor transmission—one grain of water vapor per square foot per hour per inch of mercury pressure difference. 1 Perm = 1 grain/h•ft2•in. Hg = 5.74 x 10-11 kg/Pa•s•m2.
588 Permeability - (1) the capacity of a porous material to conduct or transmit fluids; (2) the time rate of vapor transmission through unit area of flat material of unit thickness induced by unit vapor pressure difference between two specific surfaces, under
589 Permeance - (1) the rate of water vapor transmission per unit area at a steady state through a material, membrane, or assembly; (2) the time rate of water vapor transmission through unit area of flat material or construction induced by unit vapor pressure
590 Petroleum pitch - A dark brown to black, predominantly aromatic, solid cementitious material obtained by the processing of petroleum, petroleum fractions, or petroleum residuals.
591 pH - a measure of the acidity or alkalinity of a solution, with neutrality represented by a value of 7, with increasing acidity represented by increasingly smaller values, and with increasing alkalinity represented by increasingly larger values.
592 Phased application - the installation of a roofing or waterproofing system during two or more separate time intervals or different days. Application of surfacings at different time intervals are typically not considered phased application. (see Surfacing.
593 Phenolic plastics - Plastics based on resins made by the condensation of phenols, such as phenol and cresol, with aldehydes.
594 Picture framing - A rectangular pattern of ridges in a membrane over insulation or deck joints.
595 Pigment - an insoluble compounding material used to impart color.
596 Pig spout - A sheet metal flashing designed to direct the flow of water out through the face of the gutter rather than through a downspout.
597 PIMA - Polyisocyanurate Insulation Manufacturers Association
598 Pinhole - A tiny hole in a coating, film, foil, or laminate comparable in size to one made by a pin.
599 Pipe boot - prefabricated flashing piece used to flash around circular pipe penetrations.
600 Pitch - See Incline; Coal Tar Pitch; or Petroleum Pitch.
601 Pitch-pocket (Pitch-pan) - a flanged, open bottomed enclosure made of sheet metal or other material, placed around a penetration through the roof, filled with grout and bituminous or polymeric sealants to sealants to seal the area around the penetration.
602 Pittsburgh lock seam - a method of interlocking metal, usually at a slope change.
603 Plastic - A material that contains as an essential ingredient one or more organic polymeric substances of large molecular weight. It is solid in its finished state and at some stage in its manufacture or processing into finished articles can be shaped by
604 Plastic cement - a roofing industry generic term used to describe asphalt roof cement that is a trowelable mixture of solvent-based bitumen, mineral stabilizers, and other fibers and/or fillers. Generally, intended for use on relatively low slopes, not ve
605 Plastic Film - a flexible sheet made by the extrusion of thermoplastic resins.
606 Plasticizer - Material, frequently solvent-like, incorporated in a plastic or a rubber to increase its ease of workability, flexibility, or extensibility. Adding the plasticizer may lower the melt viscosity, the temperature of the second order transition,
607 Plasticizer migration - in some thermoplastic roofing membranes, the loss of plasticizer chemicals from the membrane, resulting in shrinkage and embrittlement of the membrane, typically PVC.
608 Plasticizers - May be monomeric liquids (phthalate esters), low molecular weight liquid polymers (polyesters) or rubbery high polymers (EVA). The most important use of plasticizers is with PVC where the choice of plasticizer dictates under what conditions
609 Plastomeric - a plastic-like polymer consisting of any of various complex organic compounds produced by polymerization, and capable of being molded, extruded, or cast into various shapes or films.
610 Pliability - the material property of being flexible or moldable.
611 Ply - A layer of felt in a roofing membrane; a four-ply membrane should have at least four plies of felt at any vertical cross section cut through the membrane.
612 Ply (Plywood)—A single veneer lamina in a glued plywood panel.
613 Plywood - A flat panel built up of sheets of wood veneer called plies, united under pressure by a bonding agent to create a panel with an adhesive bond between plies as strong as or stronger than, the wood. Plywood is constructed of an odd number of layer
614 PMR - protected membrane roof.
615 Pointing—(1) Troweling mortar into a joint after masonry units are laid. (2) Final treatment of joints in cut stonework. Mortar or putty-like filler is forced into the joint after the stone is set.
616 Polychloroprene - see Neoprene.
617 Polyester - a polymer in which the repeated structural unit in the chain is of the ester type.
618 Polyester fiber - Generic name for a manufactured fiber in which the fiber-forming substance is any long chain synthetic polymer composed of an ester of a dihydric alcohol and terephthalic acid. Scrims made of polyester fiber are used for fabric reinforce
619 Polyisobutylene - The polymerization product of isobutylene varying in consistency from a viscous liquid to a rubberlike solid, with corresponding variation in molecular weight from 1,000 to 400,000. May be compounded for use as a roof membrane material.
620 Polyisocyanurate - Thermoset polymer formed by polymerization of isocyanate; rigid foam insulation meeting ASTM C1289; a thermal insulation similar in appearance to polyurethane foam, but with improved fine resistance or rating.
621 Polymer - A macromolecular material formed by the chemical combination of monomers having either the same or different chemical composition. Plastics, rubbers, and textile fibers are all high molecular weight polymers.
622 Polymer modified bitumen - see Modified bitumen.
623 Polymeric methylene diphenyl diisocyanate (PMDI) - component A in SPF. An organic chemical compound having two reactive isocyanate groups. It is mixed with the B component to form polyurethane.
624 Polymerization - a chemical reaction in which monomers are linked together to form polymers.
625 Polyol - a polyhydric alcohol, i.e., one containing three or more hydroxyl groups, one component of polyisocyanurate and polyurethane compounds.
626 Polypropylene - a polymer prepared by the polymerization of propylene as the sole monomers.
627 Polystyrene - a polymer prepared by the polymerization of styrene as the sole monomer.
628 Polyvinyl Chloride (PVC) - A synthetic thermoplastic polymer prepared from vinylchloride. PVC can be compounded into flexible and rigid forms through the use of plasticizers, stabilizers, filler, and other modifiers; rigid forms used in pipes; flexible fo
629 Pond - A roof area that retains water instead of draining after rainfall.
630 Ponding - the excessive accumulation of water at low-lying areas on a roof that remains after the 48 hours after the end rainfall under conditions conducive to drying.
631 Pop rivet - a relatively small-headed pin with an expandable head for joining light gauge sheet metal.
632 Popcorn surface texture - in SPF roofing, the condition in which the foam surface shows a coarse texture where valleys form sharp angles. This surface is unacceptable for proper coating and protection.
633 Positive drainage - the drainage condition in which consideration has been made during design for all loading deflections of the deck and additional roof slope has been provided to ensure drainage of the roof area within 48 hours of rainfall during condit
634 Positive side waterproofing - an application where the waterproofing systems and the source of the hydrostatic pressure are on the same side of the structural element.
635 Pot life (Working life) - the period of time during which a reacting composition remains suitable for its intended processing after mixing with reaction initiating agents.
636 Pourable sealer - a type of sealant often supplied in two parts and used at difficult-to-flash penetrations, typically in conjunction with pitch-pockets to form a seal.
637 Pre-tinning - coating a metal with solder or tin alloy prior to soldering or brazing it.
638 Pre-painted coil - Coil steel which receives a paint coating prior to the forming operation.
639 Pre-tinning - coating a metal with solder or tin alloy prior to soldering or brazing it.
640 Press brake - A machine used in cold-forming metal sheet or strip into desired profiles.
641 Prestressed concrete - Concrete in which the reinforcing cables, wires, or rods in the concrete are tensioned before there is load on the member, holding the concrete in compression for greater strength.
642 Preventive maintenance - The regular, scheduled, inspection for and the repair of normal, expected breakdown of materials and equipment.
643 Prime coat - First liquid coat applied in a multiple coat system.
644 Primer-(1) a thin, liquid-applied solvent-based bitumen that may be applied to a surface to improve the adhesion of subsequent applications of bitumen; (2) a material which is sometimes used in the process of seaming single-ply membranes to prepare the su
645 Proportioner - the basic pumping unit for SPF or two-component coating systems. Consists of two positive displacement pumps designed to dispense two components at a precisely controlled ratio.
646 Protected membrane roof (PMR) - an insulated and ballasted roofing assembly in which the insulation and ballast are applied on top of the membrane (sometimes referred to as an "inverted roof assembly").
647 Protection course - a sacrificial material used to shield a waterproofing material from damaging external forces.
648 Psychrometer - an instrument used to measure humidity in the atmosphere from two thermometers which are similar except that the bulb of one is kept wet, the bulb of the other being dry.
649 Psychrometric chart - chart showing the relationship between dew point temperature, dry bulb temperature, wet bulb temperature and relative humidity.
650 Puncture resistance - the ability of a material to withstand the action of a penetrating or puncturing object.
651 Purlin - horizontal secondary structural member that transfers loads from the primary structural framing.
652 PVC - polyvinyl chloride.
653 R-Factor - Resistance to heat flow. The summation of individual thermal resistances in an assembly.
654 R-value - see Thermal resistance.
655 Racking - a method of asphalt shingle application, also referred to as the straight-up method, whereby shingle courses are applied vertically, up the roof rather than laterally or across and up.
656 Rafter
657 one of a series of sloped structural members, that extend from the ridge or hip to the downslope perimeter or eave, designed to support the roof deck and its associated loads.
658 Raggle - a groove or slot, often cut in a masonry wall or other vertical surface adjoining a roof, for inserting an inset flashing component such as a reglet.
659 Rake - The sloped edge of a roof at the first or last rafter.
660 Rake angle - Angle fastened to purlins at rake for attachment of endwall panels.
661 Rake-starter (Bleeder strip) - starter-strip used along rake edges in conjunction with asphalt shingle roofing.
662 RCI - Roof Consultants Institute
663 RCMA - Roof Coatings Manufacturers Association
664 RDCA - Roof Deck Contractors Association
665 Re-cover - the addition of a new roof membrane or steep-slope roof covering over a major portion of an existing roof assembly. This process does not involve removal of the existing roofing.
666 Reflectivity - see Light reflectance.
667 Reglet - a sheet metal receiver for the attachment of counterflashing. A reglet may be surface-mounted, inset into a raggle or embedded behind cladding.
668 Reinforced membrane - a roofing or waterproofing membrane that has been strengthened by the addition or incorporation of one or more reinforcing materials, including woven or nonwoven glass fibers, polyester mats or scrims, nylon, or polyethylene sheeting
669 Relative humidity - The ratio of the mass per unit volume (or partial pressure) of water vapor in an air-vapor mixture to the saturated mass per unit volume (or partial pressure) of the water vapor at the same temperature, expressed as a percentage.
670 Release tape (or strip) - a plastic film or paper strip that is applied to the back of self-sealing shingles and other materials. The strip prevents the material from sticking together in the roll or bundle. With asphalt shingles, the strip need not be re
671 Replacement - the practice of removing an existing roof system down to the roof deck and replacing it with a new roofing system.
672 Remedial roofing - The repair of selected isolated portions of the roof system to return the roof to uniform condition. This normally involves the removal of wet materials along with correction of the original cause of the problem.
673 Reroofing - the process of re-covering, or tearing-off and replacing an existing roof system.
674 Resin - component B in SPF. This component contains a catalyst, blowing agent, fire retardants, surfactants and polyol. It is mixed with the A component to form polyurethane.
675 Resistance, Thermal - the average temperature difference between two defined surfaces of a particular body or assembly when unit thermal transmission in unit time through unit area is established between the surfaces. R=_Fòhòsòft2/Btu (R=Kòm2/W).
676 Retrofit - the modification of an existing building or facility to include new systems or components.
677 Ridge - Highest point on the roof of the building, a horizontal line running the length of the building.
678 Ridge cap - A material or covering applied over the ridge of a roof.
679 Ridge course - the last or top course of roofing materials, such as tile, roll roofing, shingles, etc., that covers the ridge and overlaps the intersecting field roofing.
680 Ridge vent - a ventilator located at the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity. 
681 Ridging - An upward, tenting displacement of a membrane, frequently over an insulation joint.
682 RIEI - Roofing Industry Educational Institute
683 RMA - Rubber Manufacturers Association
684 Roll goods - A general term applied to rubber and plastic sheeting, usually furnished in rolls.
685 RMA - Rubber Manufacturers Association
686 Roll roofing - Coated felts, either smooth or mineral surfaced.
687 Roof - (1) the cover of a building; (2) to cover with a roof.
688 Roof area divider - refer to area divider.
689 Roof area expansion joint - see expansion joint.
690 Roof assembly - an assembly of interacting roof components including the roof deck, vapor retarder (if present), insulation, and roof covering.
691 Roof cement - see Asphalt roof cement or Coal tar roof cement.
692 see Flashing Cement.
693 Roof covering - the exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.
694 Roof curb - raised frame used to mount mechanical units (such as air conditioning or exhaust fans), skylights, etc. on a roof.
695 Roof Diaphragm - a structural roof deck that is capable of resisting shear that is produced by lateral forces, such as wind or seismic loads.
696 Roofer - craftsman who applies roofing materials.
697 Roof jack - An accessory used to cover pipes (such as vents or flues) that penetrate the roof panel.a metal or wood bracket used to support toe-boards on steep-slope roofs. (also see Flashing Collar.)
698 Roof or Roofer's Cement - see Asphalt Roof Cement or Coal Tar Roof Cement.
699 Roof overhang - A roof extension beyond the endwall/sidewall of a building.
700 Roof seamer - Machine that crimps panels together or that welds laps of E/P systems using heat, solvent or dielectric energy.
701 Roof slope - the angle a roof surface makes with the horizontal, expressed as a ratio of the units of vertical rise to the units of horizontal length (sometimes referred to as run). For English units of measurement, when dimensions are given in inches, sl
702 Roofing system - a system of interacting roof components, generally consisting of membrane or primary roof covering and roof insulation (not including the roof deck) designed to weatherproof and, sometimes, to improve the building's thermal 
703 resistance.
704 Rosin paper (specifically Rosin-sized sheathing paper) - a nonasphaltic paper used as a sheathing paper or slip sheet in some roof systems.
705 Rubber - A material capable of quickly recovering from large deformations, normally insoluble in boiling solvent such as benzene, methyl ethyl ketone, and ethanol toluene azeotrope. A rubber in its modified state retracts within 1 mm to less than 1.5 time
706 Run - horizontal dimension of a slope.
707 Rust Blush - the earliest stage of rusting characterized by the orange or red color. Occurs frequently on freshly sand blasted steel if allowed to stand too long before coating.
708 Saddle - A small structure that helps to channel surface water to drains. Frequently located in a valley, a saddle is often constructed like a small hip roof or like a pyramid with a diamond-shaped base (also see Cricket).
709 Sag - undesirable excessive flow in material after application to a surface.
710 Sandwich panel - A panel assembly used as covering; consists of an insulating core material with inner and outer skins.
711 Saturated felt - a felt that has been immersed in hot bitumen; the felt adsorbs as much bitumen as it can retain under the processing conditions, but remains porous and contains voids.
712 SBA - Systems Builders Association
713 SBCCI - Southern Building Code Congress International, Inc. 
714 SBS - see Styrene butadiene styrene.
715 Scarf - To scrap or abrade a surface to remove degraded or wet polyurethane foam. 
716 Scarfed - shaped by grinding.
717 Screeding - the process of striking off excess concrete to bring the top surface of the concrete to the proper finish and elevation.
718 Screen wall - a nonstructural wall erected around units or curbs on a roof. Typically the framing consists of girts with a wood or metal covering attached to the frame.
719 Scrim - a woven, nonwoven or knitted fabric composed of continuous strands of material used for reinforcing or strengthening membranes. 
720 Scupper - Channel through parapet, designed for peripheral drainage of the roof, usually a safety overflow to limit accumulation of ponded rainwater caused by clogged drains. Drainage device in the form of an outlet through a wall, parapet wall or raised
721 Scuttle - a hatch that provides access to the roof from the interior of the building.
722 SDI - Steel Deck Institute.
723 Seal - (1) a generic term for a function that prevents or controls the passage of water; (2) to secure a roof or structure from the entry of moisture.
724 Sealant-(1) a material that has the adhesive and cohesive properties to form a seal; (2) a mixture of polymers, fillers, and pigments used to fill and seal joints where moderate movements is expected; unlike caulking, it cures to a resilient solid.
725 Sealant backing - a compressible material placed in a joint before applying a sealant.
726 Sealer - a coating designed to prevent excessive absorption of finish coats into porous surfaces; a coating designed to prevent bleeding.
727 Sealing washer - a rubber or neoprene washer, sometimes metal-backed, typically placed on a fastener to prevent water from migrating into a through the fastener hole.
728 Seam - a joint formed by mating two separate sections of material. Seams can be made or sealed in a variety of ways, including adhesive bonding, hot-air welding, solvent welding, using adhesive tape, sealant, etc.
729 Seam sample - in single-ply and sometimes modified bitumen membrane roofing, a sample from the membrane that extends through the side lap of adjacent rolls of membrane, taken for the purpose of assessing the quality of the seam.
730 Seam strength - Strength of a seam of material measured either in shear or peel modes, reported either in absolute units, e.g., pounds per inch of width--or as a percent of the sheeting strength.
731 Self-adhering membrane - a membrane that can adhere to a substrate and to itself at overlaps without the use of an additional adhesive. The undersurface of a self-adhering membrane is protected by a release paper or film, which prevents the membrane from
732 Self-drilling screw - A fastener that drills and taps its own hole, used as a fastener for attaching panels to purlins and girts.
733 Self-sealing shingle - an asphalt shingle containing factory-applied strip or spots of heat sensitive adhesive intended to adhere the overlying shingle once installed on the roof and warmed by the sun.
734 Self-tapping screw - A fastener that forms receiving threads when turned into a previously drilled hole. It is for attaching panels to purlins and girts and for 
735 connecting trim and flashing.
736 Self-Vulcanized Membrane - a membrane manufactured from compounds that are thermoplastic during manufacture and installation, but whose polymers eventually cross-link and cure during exposure.
737 Selvage - (1) an edge or edging that differs from the main part of a fabric, granule-surfaced roll roofing or cap sheet, or other material; (2) a specially defined edge of the material (lined for demarcation), which is designed for some special purpose, s
738 Selvage Edge - an edge designed for certain sheet good materials, e.g., mineral-surfaced sheets. With mineral surfaced sheets, the surfacing is omitted over a portion of the longitudinal edge of the sheet (e.g., mineral surface cap sheet) in order to obta
739 Separator layer - refer to Slip sheet.
740 Service life - Anticipated useful life of a building, building component or building subsystem (e.g., roof system).
741 Service temperature limits - the minimum or maximum temperature at which a coating, SPF, or other material will perform satisfactorily.
742 Set - to convert into a fixed or hardened state by chemical or physical action.
743 Shading - slight differences in surfacing color, such as shingle granule coloring, that may occur as a result of manufacturing operations.
744 Shark fin - Curled felt projecting upward through the flood coat and aggregate of a BUR membrane.
745 Shear - The force tending to make two contacting parts slide upon each other in opposite directions parallel to their plane of contact.
746 Shear strength - the resistance to forces that cause or tend to cause two contiguous parts of the body to slide relative to each other in a direction parallel to their contrast.
747 Shed roof - a roof having only one sloping plane and no hips, ridges or valleys.
748 Sheeting - A form of plastic or rubber in which the thickness is very small in proportion to length and width and in which the polymer compound is present as a continuous phase throughout, with or without fabric.
749 Shelf life - the maximum time a package material can be stored under specified conditions and still meet the performance requirements specified.
750 Shingle—(1) A small unit of prepared roofing designed for installation with similar units on overlapping rows on inclines normally exceeding 25%; (2) T o cover with shingles, and (3) T o apply any sheet material in overlapping rows like shingles.
751 Shingling—(1) The procedure of laying parallel felts so that one longitudinal edge of each felt overlaps, and the other longitudinal edge underlaps an adjacent felt. (See also Ply). Normally, felts are shingled on a slope so that the water flows over rath
752 Shore "A" Hardness - a measure of firmness of a material by means of a Durometer Hardness Gauge. (A measure of 20 is about the firmness of a gum eraser; 90 is about that of a rubber heel.)
753 Shrinkage - a decrease in one or more dimensions of an object or material.
754 Shrinkage crack - in waterproofing, a separation in a material, such as a concrete substrate, caused by the inability of the material to resist a reduction in size which occurs during its hardening or curing process or both.
755 SI - an abbreviation for the International System of Units (Le Systeme International d'Unites).
756 Side lap - the continuous longitudinal overlap of neighboring like materials. 
757 Side lap fastener - a fastener used to connect adjacent panels together at the side lap.
758 Siding - the finish covering of an exterior wall of a frame building; the siding may be cladding material such as wood, aluminum or vinyl (but not masonry).
759 Sieve - An apparatus with square apertures for separating sizes of material.
760 Silicone-based Water Repellants - any of the organopolysiloxanes (silicone derivative) applied to masonry materials for dampproofing or repelling water.
761 Sill - The bottom horizontal framing member of an opening such as a window or door.
762 Sill flashing - a flashing of the bottom horizontal framing member of an opening, such as below a window or door.
763 Single Coverage - roofing material that provides one layer over the substrate to which it is applied.
764 Single-lock standing seam - a standing seam that uses one overlapping interlock between two seam panels, in contrast with the double interlocking used in a double standing seam.
765 Single-ply membranes - roofing membranes that are field applied using just one layer of membrane material (either homogeneous or composite) rather than multiple layers.
766 Single-ply roofing - a roofing system in which the principal roof covering is a single layer flexible membrane often of thermoset or thermoplastic membrane.
767 Single-Ply System - generally, there are six types of single-ply roofing systems 1) Fully-adhered 2) Loose-laid 3) Mechanically-fastened 4) Partially-adhered 5) Protected membrane roof 6) Self-adhering
768 Single slope - A sloping roof with one surface. The slope is from one wall to the opposite wall of rectangular building.
769 Siphon break - A small groove to arrest the capillary action of two adjacent surfaces.
770 Skinning - the formation of a dense film on the surface of a liquid coating or mastic.
771 Skirt flashing - a formed metal counterflashing secured under a mechanical unit or skylight to cover and protect the upper edge of a base flashing and its associated fasteners.
772 Skylight - an opening in a roof that is glazed with a transparent or translucent material; used to admit diffused light to the space below.
773 Slab - A semi-finished steel product, intermediate between ingot and plate, with the width at least twice the thickness.
774 Slab-on-grade - a horizontal placement of concrete placed directly over a prepared earth substrate.
775 Slag - a hard aggregate that is left as a residue from blast furnaces, which may be used as a surfacing material on certain (typically bituminous) roof membrane systems.
776 Slate - a hard, brittle metamorphic rock consisting mainly of clay minerals, used extensively as dimensional stone for steep roofing and in granular form as surfacing on some other roofing materials.
777 Slating hook - a steep-slope roofing attachment device, shaped like a hook, that can be used for fastening roofing slate.
778 Slip sheet - sheet material, such as reinforced kraft paper, rosin-sized paper, polyester scrim or polyethylene sheeting, placed between two components of a roof assembly (such as between membrane and insulation or deck) to ensure that no adhesion occurs
779 Slit sample - in SPF roofing, a small cut about 1 inch x 1/2 inch (25 mm x 13 mm x 13 mm), in a half-moon shape, used to measure coating film thickness.
780 Slippage - Relative lateral movement of adjacent felts (or sheets) in a roof membrane. It occurs mainly in roofing membranes on a slope, sometimes exposing the lower plies or even the base sheet to the weather.
781 Slope - Tangent of the angle between the roof surface and the horizontal plane, expressed as a percentage, or in inches of rise per foot of horizontal distance. (See also Incline and Roof Slope).
782 SMACNA - Sheet Metal and Air Conditioning Contractors National Association.
783 Smooth surfaced roof - A roof membrane without mineral aggregate surfacing.
784 Smooth surface texture - in SPF roofing, the condition of the foam in which the surface shows spray undulation and is ideal for receiving a protective coating.
785 Snap-on cap - a separate cap that snaps on over the vertical legs of some single standing or batten seam metal roof systems.
786 Snow guard - a series of devices attached to the roof in a pattern that attempts to hold snow in place, thus preventing sudden snow or ice slides from the roof; any device intended to prevent snow from sliding off a roof.
787 Snow load - the live load due to the weight of snow on a roof; included in design calculations.
788 Soffit - The exposed underside covering of any exterior overhanging section of a roof eave, gable or sidewall. 
789 Soffit vent - a premanufactured or custom built air inlet source located at the downslope eave or in the soffit of a roof assembly.
790 Softening point - the temperature at which bitumen becomes soft enough to flow, as determined by an arbitrary, closely defined method (ASTM Standard test method D 36 or D 3461).
791 Softening point drift - a change in the softening point of bitumen during storage or application. (see Fallback.)
792 Soil stack - a sanitation pipe that penetrates the roof; used to vent plumbing fixtures.
793 Solder - a lead/tin mixture that is melted and used to bond two pieces of some metals together.
794 Solid mopping - A continuous mopping of a surface.See Mopping. Sprinkle mopping—See Mopping.
795 Solids content - the percentage by weight of the nonvolatile matter in an adhesive.
796 Solvent - any liquid used to dissolve another material.
797 Solvent cleaners - used to clean some single-ply roofing membranes prior to splicing, typically including heptane, hexane, white gasoline, and unleaded gasoline.
798 Solvent welding - a process where a liquid solvent is used to chemically weld or join together two or more layers of certain membrane materials (usually thermoplastic).
799 Spalling - breaking off of plate-like pieces from a concrete, rock or masonry surface.
800 Special steep asphalt - asphalt complying with ASTM D 312, Type IV. (See Asphalt.)
801 Specification - a precise statement of a set of requirements to be satisfied by a material, product, system, or service.
802 SPF - sprayed polyurethane foam.
803 SPFA - Sprayed Polyurethane Foam Alliance (a business unit of the American Plastics Council).
804 SPF compound - a term used to describe the raw materials (isocyanate and resin) used to make polyurethane foam.
805 SPI - The Society of the Plastics Industry
806 SPI/SPFD - The Society of the Plastics Industry/Sprayed Polyurethane Foam Division
807 Splash block - a small masonry or polymeric block laid on the ground or lower roof below the opening of a downspout used to help prevent soil erosion and aggregate scour in front of the downspout.
808 Splice - bonding or joining of overlapping materials. (see Seam.)
809 Splice plate - a metal plate placed underneath the joint between two pieces of metal.
810 Split - a membrane tear resulting from tensile stresses.
811 Split Sheet - see Nineteen-Inch Selvage.
812 Split slab - a term used to describe two separate concrete slabs. The first is placed as a slab on grade or suspended slab, and covered with waterproofing and a drainage system. The second slab, also referred to as a topping slab, is then placed over the
813 Splice-tape - cured or uncured synthetic rubber tape used for splicing membrane materials.
814 Spot Mopping - a mopping pattern in which hot bitumen is applied in roughly circular areas, leaving a grid of unmopped, perpendicular bands on the roof.
815 Sprayed polyurethane foam (SPF) - a foamed plastic material, formed by spraying two components, PMDI (A component) and a resin (B component) to form a rigid, fully adhered, water-resistant, and insulating membrane.
816 Spread coating - a manufacturing process in which membranes are formed using a liquid compound that is spread onto a supporting reinforcement base layer and then dried to its finished condition.
817 SPRI - Single Ply Roofing Institute
818 Sprinkle Mopping - a random mopping pattern in which heated bitumen beads are strewn onto the substrate with a brush or mop.
819 Spud - To remove the roofing aggregate and most of the bituminous top coating by scraping and chipping.
820 Spudder - Heavy steel implement with a dull, bevel-edged blade for removing embedded aggregate from a BUR membrane surface.
821 Spunbond - a type of nonwoven fabric formed from continuous fiber filaments that are laid down and bonded continuously, without an intermediate step.
822 Spunlaced - a nonwoven fabric made by mechanically bonding a dry-laid staple fabric by water jet, which entangles the individual fibers.
823 Square-tab shingles - shingles with tabs that are all the same size and exposure.
824 Square - a unit used in measuring roof area equivalent to 100 square feet (9.29 m2) of roof area.
825 Squeegee - (1) a blade of leather or rubber set on a handle and used for spreading, pushing or wiping liquid material on, across or off a surface; (2) to smooth, wipe or treat with a squeegee.
826 Stack vent - A vertical outlet designed to relieve pressure exerted by water vapor between a membrane and the vapor retarder or deck.
827 Stainless steel - An alloy of steel which contains a high percentage of chromium. Also may contain nickel or copper. Has excellent resistance to corrosion.
828 Standing seam - Watertight seam type featuring an upturned rib, which may also be structural. It is made by turning up the edges of two adjacent metal panels and then folding them over in one of a variety of ways.
829 Standing water test - Evaluations in which test panels are submerged in aqueous solutions and alternately dried in air.
830 Starter course - the first layer of roofing, applied along a line adjacent to the downslope perimeter of the roof area. With steep-slope watershedding roof coverings, the starter course is covered by the first course.
831 Starting platform - A movable platform used to support a seaming machine as it begins to roll- seal a metal seam.
832 Starter sheets - (1) felt, ply sheet or membrane strips that are made or cut to widths narrower than the standard width of the roll and used to start the shingling pattern at an edge of the roof; (2) particular width sheets designed for perimeters in some
833 Starter strip - roll roofing or shingle strips applied along the downslope eave line before the first course of roofing and intended to fill spaces between cutouts and joints of the first course.
834 Static load - any load, as on a structure, that does not change in magnitude or position with time.
835 Steel - a malleable alloy of iron and carbon produced by melting and refining pig iron and/or scrap steel; graded according to the carbon content (in a range from 0.02 to 1.7%); other elements, such as manganese and silicon, may be included to provide spe
836 Steel joist (open web steel joist) - normally used as a horizontal supporting member between beams or other structural members, suitable for the support of some roof decks.
837 Steep asphalt - A relatively viscous roofing asphalt conforming to the requirements of Specification D312, Type Ill.
838 Steep-Slope Roofing - a category of roofing that includes water shedding types of roof coverings installed on slopes exceeding 3 12 or 25%.
839 Steep-slope roofs - a category of roofing that generally include water-shedding types of roof coverings installed on slopes exceeding 3:12 (14 degrees).
840 Steeple - a tower or spire, usually located on a church.
841 Step flashing - individual pieces of sheet metal material used to flash walls, around chimneys, dormers and such projections along the slope of a roof. Individual pieces are overlapped and stepped up the vertical surface.
842 Stick clip - in waterproofing, a non-penetrating fastener that is adhered to the waterproofing surface; typically used to retain insulation, drainage panels, prefabricated protection materials, etc., against the waterproofing to prevent sliding and displa
843 Stiffener rib - small intermediate bends in a metal pan used to strengthen the panel.
844 Storm anchor - see Wind Clip.
845 Strain - the dimensionless expression for the elongation of a material under stress. Strain is expressed as the ratio of elongation per unit length.
846 Strapping (felts) - a method of installing roofing rolls or sheet good materials parallel with the slope of the roof.
847 Straw nail - a long-shanked nail. Sometimes used for fastening over tile at hips and ridges.
848 Strawberry - See Blueberry.
849 Stress—(1) A measure of the load on a structural member in terms of force per unit area (Mpa) (kips per sq. in.); (2) The force acting across a unit area in solid material in resisting the separation, compacting or sliding that tends to be induced by exte
850 Stress concentration - A condition in which stress is highly localized, usually induced by an abrupt change in the shape of a member or at a substrate joint (e.g., between insulation joints) 
851 Stress-Crack - external or internal cracks within a material caused by long-term stress. Environmental factors, such as contact with corrosive material, usually accelerate stress-cracking.
852 Stress relaxation - The time-dependent change in the stress resulting from application of a constant total strain to a specimen at a constant temperature. The stress-relaxation at a given elapsed time is equal to the maximum stress resulting when the stra
853 Striations - a parallel series of small grooves, channels, or impressions typically within a metal roof panel used to help reduce the potential for oil-canning.
854 Strike-through - A term used in the manufacture of fabric reinforced polymeric sheeting to indicate that two layers of polymer have made bonding contact through the reinforcing scrim.
855 Strip Mopping - a mopping pattern in which hot bitumen is applied in parallel bands.
856 Strip shingles - asphalt shingles that are manufactured in strips, approximately three times as long as they are wide.
857 Strippable films - (for metal) added protection of plastic films sometimes applied to coated or finished metals after the coil coating process. Applied after prime and top coats to resist damage to the finish prior to and during shipping, fabrication, and
858 Stripping in - application of membrane stripping ply or plies.
859 Stripping—Strip flashing: (1) The technique of sealing a joint between metal and bituminous membrane with one or two plies of felt or fabric and hot- or cold-applied bitumen; (2) The technique of taping joints between insulation boards or deck panels.
860 Structural panel - a metal roof panel designed to be applied over open framing rather than a continuous or closely spaced roof deck.
861 Styrene butadiene rubber
862 high molecular weight polymers having rubber-like properties, formed by the random copolymerization of styrene and butadiene monomers.
863 Substantial Completion - The stage in the progress of the work when it is sufficiently complete for the owner to occupy or utilize the work for its intended use.
864 Substrate - Surface upon which a roof component is placed (structural deck or insulation).
865 Sump - an intentional depression around a roof drain or scupper that promotes drainage.
866 Sump pan - a metal pan used to create a depression around a drain or scupper to enhance drainage.
867 Superimposed loads - loads that are added to existing loads. For example, a large stack of insulation boards placed on top of a structural steel deck.
868 Super-steep asphalt - A high viscosity roofing asphalt conforming to the requirements of Specification D312, Type IV.
869 Supported sheeting - See Fabric Reinforcement.
870 Surface Conductance - a unit of heat flow or heat exchange between a material and the air around it. Ventilation over a surface will decrease the thickness of the air film and reduce the thermal effect (increase the heat flow).
871 Surface cure - Curing or vulcanization which occurs in a thin layer on the surface of a manufactured polymeric sheet or other items.
872 Surface Dryness - surface dryness can be evaluated qualitatively by taping an 18 inch by 18 inch (0.46 m by 0.46 m) clear 4 mil polyethylene sheet to a concrete surface, and observing the moisture that may collect on the underside of the polyethylene shee
873 Surface erosion - the wearing away of a surface due to abrasion, dissolution or weathering.
874 Surface texture - the resulting surface from the final pass of SPF. The following terms are used to describe the different SPF surface textures: smooth orange peel, coarse orange peel, verge of popcorn, popcorn, treebark, and oversprayed.
875 Surfacing - the top layer or layers of a roof covering, specified or designed to protect the underlying roofing from direct exposure to the weather.
876 Surfactants - Surface active agents that reduce surface tension when dissolved in water or water solutions, or reduce interfacial tension between two liquids, or between a liquid and a solid.
877 Synthetic Rubber - any of several elastic substances resembling natural rubber, prepared by the polymerization of butadiene, isoprene, and other unsaturated hydrocarbons. Synthetic rubber is widely used in the fabrication of single-ply roofing membranes.
878 Susceptibility - When not otherwise qualified, the degree of change in viscosity with temperature.
879 SWRI - Sealant, Waterproofing and Restoration Institute
880 T-joint - the condition created by the overlapping intersection of three or four sheets in the membrane.
881 Tab - the exposed portion of strip shingles defined by cutouts.
882 Tack-free - A film is considered tack-free when the finger, with a slight pressure, will not leave a mark. The surface will not be sticky.
883 Tack-free time - in SPF-based roofing, a curing phase of polyurethane foam to when the material is no longer sticky. When the polyurethane foam is tack free, it can be sprayed over with another pass, referred to as a "lift". With some care the polyurethan
884 Talc - whitish powder applied at the factory to the surface of some roofing materials (e.g., vulcanized EPDM membranes), used as a release agent to prevent adhesion of the membrane to itself.
885 Tapered edge strip - A tapered insulation strip used to elevate the roofing at the perimeter and at penetrations and at curbs, and to provide gradual transition from one layer of insulation to another.
886 Taping - (1) the technique of connecting joints between insulation boards or deck panels with tape; (2) the technique of using self-adhering tape-like materials to seam or splice single-ply membranes.
887 Tar - a brown or black bituminous material, liquid or semi-solid in consistency, in which the predominating constituents are bitumens obtained as condensates in the processing of coal, petroleum, oil-shale, wood, or other organic materials.
888 Tar boils - Bubbles of moisture vapor encased in a thin film of bitumen, also known as blueberry, blackberry, etc.
889 Tarred felt - see Coal tar felt.
890 Tear resistance - the load required to tear a material, when the stress is concentrated on a small area of the material by the introduction of a prescribed flaw or notch. Expressed in psi (pounds force) per inch width or kN/m (kilonewton per meter width).
891 Tear strength - The maximum force required to tear a specified specimen, the force acting substantially parallel to the major axis of the test specimen. Measured in both initiated and uninitiated modes. Obtained value is dependent on specimen geometry, ra
892 Tear-off - Removal of a failed roof system down to the structural deck surface.
893 Tear-off and reroof - the removal of all roof system components down to the structural deck, followed by installation of a completely new roof system.
894 Tensile Fatigue Resistance - the ability of a given membrane material to resist "fatigue" and/or other damage (such as loss of elasticity) caused by the alternate stretching and relaxing of the material over a period of time.
895 Tensile strength
896 the strength of a material under tension as distinct from torsion, compression or shear.
897 Tensile Test - a test in which a specimen is subjected to increasing longitudinal pulling stress until fracture occurs.
898 Tension leveling - the process of pulling metal coil stock between two spools under a certain pressure to help reduce side camber and potential oil canning in the coil stock caused by manufacturing and cutting processes.
899 Termination - the treatment or method of anchoring and/or sealing the free edges of the membrane in a roofing or waterproofing system.
900 Terne - an alloy of lead and tin, used to coat sheets of carbon steel or stainless steel for use as metal roofing sheet.
901 Terra cotta - low-fired clay, either glazed or unglazed.
902 Test cut - a sample of the roof system or assembly which exposes the roof deck and is used to diagnose the condition of the membrane, evaluate the type and number of plies or number of membranes, or rates of application (e.g., the weight of the average in
903 Thatch Roof - the covering of a roof usually made of straw, reed, or natural foliage (palms) bound together to shed water.
904 Therm - a unit of heat equivalent to 100,000 BTUs (105.6 x 106). Commonly used by utilities in quoting prices or costs.
905 Thermal Barrier - a material applied over polyurethane foam designed to slow the temperature rise of the foam during a fire and delay its involvement in the fire. Thermal barriers for use with SPF must have a time rating of not less than 15 minutes.
906 Thermal block - a compression-resistant insulation block installed between structural steel and the panels and their supporting members to help maintain insulation R-values and reduce condensation.
907 Thermal bridge - the penetration of a material of high thermal conductivity (e.g., a metal insulation or roof membrane fastener) through a material of low thermal conductivity (e.g., thermal insulation); the result is a lowered thermal resistance for the
908 Thermal conductivity (k) - the time rate of heat flow through a unit area of a homogeneous material in a direction perpendicular to isothermal planes induced by a unit temperature gradient is called thermal conductivity (k or k-value). In English (inch-po
909 Thermal cycling - sequence of values by a repetitive temperature differential due to changes in radiant energy.
910 Thermal expansion - the increase in the dimension or volume of a body due to temperature variations.
911 Thermal Image - a visual representation of temperature distribution over a surface area. The image is displayed on a screen, presenting the response to infrared light waves.
912 Thermal insulation - A material designed to reduce the conductive heat flow.
913 Thermal movement - changes in dimension of a material as a result of temperature changes.
914 Thermal resistance (R) - under steady conditions, thermal resistance is the mean temperature difference between two defined surfaces of material or construction that induces unit heat flow through a unit area. In English (inch.pound) units it is expressed
915 Thermal shock - the stress-producing phenomenon resulting from sudden temperature changes in a roof membrane when, for example, a cold rain shower follows brilliant sunshine.
916 Thermal stress - stress introduced by uniform or non-uniform temperature change in a structure or material that is contained against expansion or contraction.
917 Thermal transmittance (U or U-factor) - thermal transmittance (U or U-factor) is the time rate of heat flow per unit area under steady conditions from the fluid (e.g., air) on the warm side of a barrier to the fluid (e.g., air) on the cold side, per unit
918 Thermogram - A visible light record of the display of an infrared camera system via a Polaroid print, 35 mm film, video tape, or a computer generated image.
919 Thermography - A technique for producing heat pictures from the invisible radiant energy emitted from stationary or moving objects at any distance and without in any way influencing the temperature of the objects under view. The electronic generation and
920 Thermoplastic - Capable of being repeatedly softened by increase of temperature and hardened by decrease in temperature. The thermoplastic form allows for easier seaming both in the factory and in the field.
921 Thermoplastic olefin membrane (TPO) - a blend of polypropylene and ethylene-propylene polymers. Colorant, flame retardants, UV absorbers, and other proprietary substances which may be blended with the TPO to achieve the desired physical properties. The me
922 Thermoplastic elastomers - Polymers capable of remelt, but exhibiting elastomeric properties; related to elasticized polyolefins. They have a limited upper temperature service range.
923 Thermoplastic resin - A material with a linear macromolecular structure that will repeatedly soften when heated and harden when cooled.
924 Thermoset - A material that will undergo (or has undergone) a chemical reaction by the action of heat, catalysts, ultraviolet light, etc., leading to a relatively infusible state.
925 Through-wall flashing - A water-resistant membrane or material assembly extending totally through a wall and its cavities, positioned to direct any water within the wall to the exterior.
926 Tensile test - A test in which a specimen is subjected to increasing longitudinal pulling stress until fracture occurs.
927 Therm - A unit of heat commonly used by utilities, equivalent to 100,000 BTU = 1.05 x 108 joules.
928 Thermal block - A spacer of low thermal conductance material, designed to prevent formation of a thermal bridge.
929 Thermal bridge - Interruption of a layer of thermal insulation by a material of high thermal conductivity (e.g. metal).
930 Thermal conductance (C) - The rate of heat flow through a material whose surfaces have stated a temperature differential Btu•in./h•ft40F(W/m2•0C).
931 Thermal conductivity (k) - The rate of heat flow
932 Thinner - (1) a volatile liquid added to an adhesive or coating material to modify the consistency or other properties; (2) a liquid used to clean equipment or other surfaces.
933 Thixotropic - the property of a material that enables it to stiffen in a relatively short time on standing, but6 upon agitation or manipulation to change to a very soft consistency or to a fluid of high viscosity, the process being completely reversible.
934 Thread Count - the number of threads per inch in each direction, with the warp mentioned first, and the fill second, (e.g., a thread count of 20 x 10 means 20 threads per inch [25.4mm] in the warp and 10 threads per inch [25.4mm] in the fill direction).
935 Through-wall flashing - a water-resistant membrane or material assembly extending totally through a wall and its cavities, positioned to direct water within the wall to the exterior, usually through weep holes.
936 Tie-in - in roofing and waterproofing, the transitional seal used to terminate a roofing or waterproofing application at the top or bottom of flashings or by forming a watertight seal with the substrate, membrane, or adjacent roofing or waterproofing syst
937 Tie-Off - (in roofing and waterproofing) the transitional seal used to terminate a roofing or waterproofing application at the top or bottom of flashings, or by forming a watertight seal with the substrate, membrane or adjacent roofing or waterproofing sy
938 TIMA - Thermal Insulation Manufacturers Association
939 Toggle bolt - a bolt having a nut with pivoted, flanged wings that close against a spring when it is pushed through a hole, and open after emerging from the hole; used to fasten objects to a hollow wall or to a wall which is accessible only from one side.
940 Tongue and groove planks - one of the oldest types of dimensional structural wood used as roof decking. The sides are cut with convex and concave grooves so adjacent planks may join in alignment with each other to form a uniform roof deck.
941 Torch-applied - method used in the installation of polymer modified bitumen membranes characterized by using open flame propane torch equipment.
942 TPA - Tri-Polymer Alloy.
943 TPO - thermoplastic olefin.
944 Traffic bearing - in waterproofing, a membrane formulated to withstand a predetermined amount of pedestrian or vehicular traffic with separate protection and a wear course.
945 Transverse seam - the joint between the top of one metal roof panel and the bottom of the next panel, which runs perpendicular to the roof slope.
946 Treebark surface texture - in SPF roofing, the surface condition of the foam which shows a coarse texture where valleys form sharp angles. This surface is unacceptable for proper coating and protection.
947 Trim—The light gauge metal used in the finish of a building, especially around openings and at intersections of surfaces. Often referred to as flashing.
948 Tuckpointing - the process of removing deteriorated mortar from an existing masonry joint and troweling new mortar or other filler into the joint.
949 Two-Part System - a coating of SPF formed by the mixing and (usually) the reaction of two different materials.
950 U-Factor—The heat flow across an entire assembly e.g., from air within a building to outside air; the inverse of R-Factor.
951 U-value - see Thermal transmittance.
952 UBC - Uniform Building Code.
953 UL - Underwriters Laboratories, Inc.
954 UL label - an identification label or seal affixed to a roofing product or package with the authorization of Underwriters Laboratories, Inc. The presence of the label indicates that the product has met certain performance criteria.
955 Ultimate elongation—The elongation of a stretched specimen at the time of break. Usually reported as percent of the original length. Also called breaking strain.
956 Ultraviolet (UV) - invisible light radiation, adjacent to the violet end of the visible spectrum, with wavelengths from about 200 to 400 nm (nanometres).
957 Underlayment - an asphalt-saturated felt or other sheet material (may be self-adhering) installed between the roof deck and the roof covering, usually used in a steep-slope roof construction. Underlayment is primarily used to separate the roof covering fr
958 Underwriters Laboratories, Inc. (UL) - an organization that tests, rates and classifies roof assemblies for their resistance to fire, impact, leakage, corrosion of metal components and wind uplift.
959 Uplift - see Wind uplift.
960 Unsupported sheeting—A polymer sheeting one or more plies thick without a reinforcing fabric layer or scrim.
961 Uplift—Wind load on a building, which causes a load in the upward direction. (See Suction)
962 Valley - the internal angle formed by the intersection of two sloping roof planes. 
963 Valley gutter—A channel used to carry off water at the intersection of two sloping roof planes.
964 Vapor barrier—See Vapor Retarder.
965 Vapor migration—The flow of water vapor from a region of high vapor pressure to a region of lower vapor pressure.
966 Vapor pressure—the pressure exerted by a vapor from a region of high vapor pressure to a region of lower vapor pressure.
967 Vapor retarder—a layer(s) of material or a laminate used to appreciably reduce the flow of water vapor into a roof assembly.
968 Vent—Opening designed to convey water vapor or other gas from inside a building or a building component to the atmosphere.
969 Ventilation Short Circuit-(as it relates to a passive ventilation system where the system is designed for air flow between intake and exhaust vents) a ventilation short circuit occurs when air is introduced into the ventilation system from an area higher
970 Ventilator—An accessory usually used on the roof that allows air to pass through. 
971 Verge of popcorn texture - in SPF roofing, the verge of popcorn surface texture is the roughest texture suitable for receiving the protective coating on a sprayed polyurethane foam roof. The surface is acceptable for receiving a protective coating only be
972 Vermiculite—An aggregate used in lightweight insulating concrete, formed by heating and expanding a micaceous mineral.
973 Viscoelastic—Characterized by changing mechanical behavior, from nearly elastic at low temperature to plastic, like a viscous fluid, at high temperature.
974 Viscosity—Index of a fluid’s internal resistance to flow, measures in centistokes (cSt) for bitumens. (Water has a viscosity of roughly 1 cSt, light cooking oil 100 cSt.)
975 Viscosity - the resistance of a material to flow under stress. For bitumen, measured in centipoise. (see Viscous.)
976 Viscous - resistant to flow under stress. 
977 Vulcanization—An irreversible process during which a rubber compound, through a change in its chemical structure, e.g., cross-linking, becomes less plastic and more resistant to swelling by organic liquids, and elastic proper- ties are conferred, improved
978 Warp—In textiles, the lengthwise yarns in a woven fabric.
979 Warm roof assembly - a roof assembly configured with each component placed immediately on top of the preceding component; each component is in contact with the adjacent component. No space is provided for ventilation of the roof assembly. Also known as a
980 Wash coat - a primer, typically provided on the back side of painted metal products to help protect the underlying metal from wear and corrosion.
981 Water Absorption - the amount of water absorbed by a material after immersion for a prescribed period of time. May be expressed as a percentage of the original weight of the material.
982 Water cure - a method of curing a material, such as concrete, by applying a fine mist of water over the surface to control the rate of moisture evaporation from the material.
983 Water cutoff - see Cutoff.
984 Waterproof - the quality of a membrane, membrane material, or other component to prevent water entry.
985 Waterproofing—Treatment of a surface or structure to prevent the passage of water under hydrostatic pressure.
986 Water-shedding - the ability of individual, overlapping components to resist the passage of water without hydrostatic pressure.
987 Water stop - a diaphragm used across a joint as a sealant, usually to prevent the passage of water.
988 Water table - the level within the ground, below which the soil is saturated with water.
989 Water vapor transmission - a measure of the rate of transmission of water vapor through a material under controlled laboratory conditions of temperature and humidity. Customary units are grains/hòft2. 
990 Wear course - the top layer of surfacing that carries pedestrian or vehicular traffic. Sometimes referred to as wearing surface.
991 Wearing surface - see Wear course.
992 Weather Infiltration - the negative condition where rain or snow penetrate the roof. The condition is typically wind-driven.
993 Weatherometer—An instrument used to subject specimens to accelerated weathering conditions, e.g., rich UV source and water spray.
994 Weatherproof - the ability of a membrane or roof covering to prevent the passage of water with a limited amount of hydrostatic pressure.
995 Weep holes - small openings whose purpose is to permit drainage of water that accumulates inside a building component (e.g., a brick wall, skylight frame, etc.).
996 Weld - to join pieces of metal together by heat fusion.
997 Wet - a condition where free water is present in a substance.
998 Wet bulb temperature - the temperature of air as registered by a thermometer whose bulb is covered by a water wetted wick. 
999 Wet film thickness - the thickness, expressed in mils, of a coating or mastic as applied but not cured. For comparison, see Dry film thickness.
1000 Wicking—The process of moisture movement by capillary action as contrasted to movement of water vapor.
1001 Wind clip - a steep-slope roofing attachment device that fits over the butt end of tile, slate and stone to help secure individual roofing units from wind uplift.
1002 Wind load - force exerted by the wind on a structure or part of a structure.
1003 Wind uplift - the force caused by the deflection of wind at roof edges, roof peaks or obstructions, causing a drop in air pressure immediately above the roof surface. 
1004 Windward - being in or facing the direction toward which the wind is blowing. The side exposed to the prevailing wind.
1005 Wire Tie System - a scheme of attachment for steep-slope roofing units (e.g., tile, slate, and stone) utilizing fasteners (nails and/or screws) in conjunction with wire to make up a concealed fastening system.
1006 Work slab - see Mud slab.
1007 Woven valley - a method of valley construction in which shingles or roofing from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied.
1008 Wythe - a masonry wall, one masonry unit, a minimum of two inches thick.
1009 Yield - in SPF-based roofing, the volume of foam per unit weight, normally expressed as board feet per pound or board feet per 1000 pounds.
1010 Yield strength—(1) The longitudinal stress a material can bear before plastic deformation (i.e., elongation under constant stress); (2) The stress at which a material exhibits a specified reduction in the constant stress/strain ratio is the elastic range.
1011 Yield strength—The stress at which a material exhibits a specified deviation from proportionality of stress and strain.
1012 Z section - a member formed in the shape of a "Z" from coiled steel stock.
1013 Zinc - a hard blush white metal, brittle at normal temperatures, very malleable and ductile when heated; not subject to corrosion; used for galvanizing sheet steel and iron, in various metal alloys, and as an oxide for white paint pigment.