Glossary of Terms

The glossary below has been created to help you translate the items that have been included in your new roof bid or any roofing terminology you have a question about. If there is any other item that you do not understand, please discuss it with your local Petersen-Dean representative by calling us at 800.564.0362. Thank you for the opportunity to provide you with information regarding your roof.

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  R  S  T  U  V  W  Z

A

AAMA: American Architectural Manufactures Association

Abrasion Resistance: the ability of a material to resist being worn away by contact with another moving, abrasive surface, such as foot traffic, mechanical equipment, wind-blown particle, etc.

Absorption: the ability of a material to accept within its body quantities of gases or liquid, such as moisture.

Accelerated Weathering: the process in which materials are exposed to a controlled environment where various exposures such as heat, water, condensation or light are altered to magnify their effects, thereby accelerating the weathering process. The material's physical properties are measured after this process and compared to the original properties of the unexposed material or to the properties of the material that has been exposed to natural weathering.

ACI: American Concrete Institute

Acid Etch: in waterproofing, use of a strong acid to cut away and remove the surface of concrete to expose the aggregate.

ACIL: American Council of INdependent Laboratories

Adhere: to cause two surface 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.

Adhesion: the state in which tow surfaces are held together by interfacial forces which may consist of molecular forces or interlocking action or both.

AFA: American Fiberboard Association

AGCA: Associated General Contractors of America

Aggregate: rock, stone, crushed stone, crushed slag, water worn gravel or marble chips used for surfacing and/or ballasting a roof system.

Aging: the effect on materials that are exposed to an environment for an interval of time.

AHA: American Hardboard Association

AIA: American Institute of Architects

Air Leakage: (as it relates to passive ventilation): negative condition where air leaks into the roof cavity (designed for use as a passive ventilation system) through cracks or openings in the structure in lieu of through the intended intake vents.

Alligatoring: the cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks similar to an alligator's hide; the cracks may or may not extend through the surfacing bitumen.

ANSI: American National Standards Institute

APA: American Plywood Association

APP: (See Atactic Polypropylene)

Application Rate: the quantity (mass, volume or thickness) of material applied per unit area.

Area Divider: a raised, flashed assembly (typically a single or double-wood member attracted to a wood base plate) that is anchored to the roof deck, it is used to relieve thermal stresses in a roof system where an expansion joint is not required or to sperate large roof areas (sometimes between expansion joints), and may be used to facilitate installation to tapered insulation. (See NRCA Construction Details.)

ARMA: Asphalt Roofing Manufactures Association

ASA: American Subcontractors Association

Asbestos: a group of natural, fibrous, impure silicate materials used to reinforce some roofing products.

ASC: Associated Specialty Contractors

ASHI: American Society of Home Inspectors

ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc.

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 specification:

Dead-level: a roofing asphalt conforming to the requirements of ASTM Specification D 312, Type I.

Flat: a roofing asphalt conforming to the requirements of ASTM Specification D 312, Type II.

Steep: a roofing asphalt conforming to the requirements for ASTM Specification D 312, Type III.

Special Steep: a roofing asphalt conforming to the requirements of ASTM Specification D 312, Type IV.

Type I: is generally referred to as "plastic cement," and is made from asphalt characterized as self-sealing, adhesive and ductile, and and conforming to ATSM Specification D 312, Type I; Specification D 449, Type I or II; or Specification D 946. (See Plastic Cement and Flashing Cement.)

Type II: is generally referred to as "vertical-grade flashing cement," and is made from asphalt characterized by high softening point and relatively low ductility, and conforming to the requirements of ASTM Specification D 312, types II or III; or Specification D 449, Types III. ( See Plastic Cement and Flashing Cement.)

ASTM: American Society for Testing and Materials

Atactic Polypropylene: a group of high molecular weight polymers formed by the polymerization of propylene.

AWPA: American Wood Preservatives Association

AWS: American Welding Society

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B

Back-nailing: (also referred to as blind-nailing): the practice of 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, course, and are not exposed to the weather in the finished roof system.

Back-surfacing: fine mineral matter applied to the back side of asphalt shingles and roll roofing to keep them from sticking together while packaged.

Ballast: an anchoring material, such as aggregate or precast concrete pavers, which employs the force of gravity to hold (or assist in holding) single-ply roof membranes in place.
Bar Joist: (See Steel Joist.)

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 axis.

Base Flashing (membrane base flashing): plies or strips of roof membrane material used to closed-off and/or seal a roof at the roof-to-vertical intersection, such as at a roof-to-wall juncture. Membrane base flashing covers the edge of the field membrane. (Also see Flashing.).

Base Ply: the lowermost ply for roofing in a roof membrane or roof system.

Base Sheet: an impregnated, saturated or coated felt placed as the first ply in some multi-ply built-up and modified bitumen roof membranes.

Batten: (1) cap or cover; (2) in a metal roof: a metal closure set over or covering the joint between, adjacent metal panels; (3) wood: a strip of wood usually set in or over the structural deck, used to elevate and /or attach a primary roof covering such as title; (4) in a membrane roof membrane and/or base flashing in place.

Beaufort Scale: a scale in which the force of the wind is indicated on a scale of 0 to 12. (See Beauford Scale chart on the following page.)

Bird Bath: random, inconsequential amounts of residual water on a roof membrane.

Bird Screen: wire mesh used to prevent birds from entering the building through ventilators, louvers, or other openings. (See Insect Screen.)

Bitumen: (1) a class of amorphous, black or dark colored, (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, soluble in carbon disulfide, and found in petroleum asphalts, coal-tars and pitches, wood tars and asphalts; (2) a generic term used to denote andy material composed principally of bitumen, typically asphalt or coal tar.

Bitumen-stop: (See Envelope and Bleed Sheet.)

Bituminous Emulsion: a suspension of minute particles of bituminous material in water or other aqueous solution. (See Asphalt Emulsion.)

Blackberry (sometimes referred to as blueberry or tar-boil): a small bubble or blister in the flood coating of an aggregate-surface built up roof membrane.

Blanket (Batt) Insulation: fiberglass or other compressible fibrous insulation, generally available in roll form.

Bleed-sheet: a sheet material used to prevent the migration of bitumen.

Blind-Nailing: the use of nails that are to exposed to the weather in the finished roofing system.

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.

Blocking: sections of wood (which may be preservative treated) built into a roof assembly, usually attracted 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 to serve as a nailer for attachment of the membrane and/or flashing.

Blowing Agent: and expanding agent used to produce a gas by chemical or thermal action or both, in manufacture of hollow or cellular materials.

BOCA: Building Officials and Code Administrators, International, Inc. (author of the BOCA National Building Code).

BOMA: Building Owners & Managers Association, International

Bond: the adhesive and/or cohesive forces holding two components in positive contact.
Bonding Agent: a chemical substance applied to a suitable substrate to create bong between it and a succeeding layer.

Boot: (1) a covering made of flexible material, which may be pre-formed 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 corners.

Brake: hand-or power-activated machinery used to form metal.

Bridging: (1) when the membrane is unsupported at a juncture; (2) bridging steep-slope roofing is a method of re-roofing over standard-sized asphalt shingles with metric-sized asphalt shingles.

Brooming: an action carried out to facilitate embedment of a ply of roofing material into hot bitumen by using a broom, squeegee or special implement to smooth out the ply and ensure contact with the bitumen or adhesive under the ply.

British Thermal Unit (BTU): the heat energy required to raise the temperature of one pound of water one degree Fahrenheit (joule).

Buckle: an upward, elongated tenting displacement of a roof membrane frequently occurring over insulation or deck joints. A buckle may be an indication of movement within the roof assembly.

Building Code: published regulations and ordinances established by a recognized agency prescribing design loads, procedures, and construction details for structures. Usually applying to designated jurisdictions (city, county, state, etc.). Building codes control design, construction, and quality of materials, use and occupancy, location and maintenance of buildings and structures within the area for which the code has been adopted.

Built-Up Roof Membrane (BUR): a continuous, semi-flexible multi-ply roof membrane, consisting of plies of layers of saturated felts, coated felts, fabric or mats between which alternate layers of bitumen are applied. Generally, built-up roof membranes are surfaced with mineral aggregate and bitumen, a liquid-applied coating or a granule-surfaced cap sheet.

Butt Joint: a joint formed by adjacent, sperate sections of material, such as where tow neighboring pieces of insulation abut.

Butyl: rubber-like material produced by copolymerizing isobutylene with a small amount of isoprene. Butyl may be manufactured in sheets or blended with other elastomeric material to make sealants and adhesives.

Butyl Rubber: a synthetic elastomer based on isobutylene and a minor amount of isoprene. It is vulcanizable and features low permeability to gases and water vapor.

Butyl Tape: a sealant tape sometimes used between metal roof panel seams, and end laps; also used to seal other types of sheet metal joints, and in various sealant applications.

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C

CABO: Council of American Building Officials

Calender: a machine with two or more counter-rotating steel rollers used for laminating sheeting or skim coating (topping) to a controlled thickness of surface characteristic or both.

Calendering: a manufacturing process by which some polymeric membranes and other sheeting are produced.

Camber: a slight convex curve of a surface, such as in a prestressed concrete deck.

Canopy: any overhanging or projecting roof structure, typically over entrances or doors. Sometimes the extreme end is unsupported.

Cant: a beveling of foam at a right angle joint for strength and water run off.

Cant Strip: a beveled or triangular-shaped strip of wood, wood fiber, perlite or other material designed to serve as a gradual transitional plane between the horizontal surface of a roof deck or rigid insulation and a vertical surface.

Cap Flashing: usually composed of metal, used to cover or shield the upper edges of the membrane base flashing, wall flashing or primary flashing. ( See Flashing and Coping).

Cap Sheet: a granule-surface coated sheet used as the top ply of some built-up or modified bitumen roof membranes and/or flashing.

Capacitance Meter: a device used to locate moisture or wet material within a roof system by measuring the ratio of the change to the potential difference between two conducting elements separated by a non-conductor.

Capillary Action: the action that causes movement of liquids by surface tension when in contact with two adjacent surfaces such as panel sidelaps.

Caulk: a material (usually a composition of vehicle and pigment) used for filling/sealing joints of junctures, where no elastomeric properties are required. (See Sealant).

Caulking: (1) the physical process of sealing a joint or juncture; (2) sealing and making weather-tight the joints, seams or voids between adjacent units by filling with a sealant.

CCF: 100 cubic feet.

Centipoise: a unit of measure of absolute viscosity. (Note: the viscosity of water is one centipoise. The lower the number, the less the viscosity.)

CERL: Construction Engineering Research Laboratory

Chalk: a powdery residue on the surface of a material.

Chalking: the degradation or migration of an ingredient, in paints, coatings or other materials.

Chlorinated Polyethylene (CPE): a thermoplastic material, used for single-ply roof membranes, composed of high molecular weight polyethylene which has been chlorinated-a process that yields a flexible rubber-like material.

Chlorosulfonated Polyethylene (CSPE or CSM) (probably best known by the DuPont tradename Hypalon): a synthetic, rubber like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produces a self-vulcanizing membrane. Classified by ASTM Standard D 5019-89.

Cladding: a material used as the exterior wall enclosure of a building.

Cleat: a metal strip, plate or metal angle piece, either continuous or individual ("clip"), used to secure two or more components together.

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.

Clip: and individual (discrete) cleat. (See Cleat.)

Closure Strip: a metal or resilient strip such as neoprene foam, used to close openings created by joining metal panels or sheets and flashings.

Coated Base Sheet: a felt that has previously been saturated (impregnated) which asphalt and later coated with harder, more viscous asphalt, which greatly increase it impermeability to moisture.

Coal Tar: a dark brown to black colored, semi-solid hydrocarbon obtained as residue from the partial evaporation of distillation of coal tars. Coal tar pitch is further refined to conform to the following roofing grade specifications:

Coal Tar Pitch: a coal tar used as the waterproofing agent in deal-level or low slope built-up roof membranes, conforming to ASTM Specification D450, Type I or Type III.

Coal Tar Waterproofing Pitch: a coal tar used as the dampproofing or waterproofing agent in below-grade structures, conforming to ASTM Specification D450, Type II.

Coal Tar Bitumen: a proprietary trade name for Type III coal tar used as the dampproofing or waterproofing agent in dead-level or low-slope built-up roof membranes, conforming to ASTM D450, Type III.

Coal Tar Felt: a felt that has been saturated with refined coal tar.

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.

Coated Base Sheet: a felt that has previously been saturated (impregnated) with asphalt and later coated with harder, more viscous asphalt, which greatly increases its impermeability to moisture.

Coated Fabric: fabrics that have been 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 material resulting from the application of a performed film to a fabric by means of calendering.

Coated Felt (sheet): (1) an asphalt-saturated felt that has also been coated on both sides with harder, more viscous "coating" asphalt; (2) a glass fiber felt that has been simultaneously impregnated and coated with asphalt on both sides.

Coefficient for Thermal Expansion: a mathematical formulation used to predict the change in dimension (typically length) of a material as a function of temperature change.

Coil Coating: the application of a finish to a coil of metal using a continuous mechanical coating process.

Cold Flow: relatively slow deformation of a material at or below room temperature. (Also see Creep).

Cold Forming: the process of using press brakes, roll formers, etc., to shape metal into desired profiles at ambient room temperature.

Cold Process Built-up Roof: 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 or adhesives installed at ambient or a slightly elevated temperature.

Cold Rolled: the process of forming steel into sheets, panels or shapes on a series of rollers at ambient room temperatures.

Color Stability: the ability of a material to retain its original color.

Collectors Box: (See Conductor Head)

Column: a primary structural member used in a vertical position
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 organic polymers. Some of the membranes listed in this generic category are CPA, EIP, NBP, and TPA.

Compressive Strength: the ability of materials and components to resist deformation or other damage caused by the weight of compression of either live or dead loads.

Condensation: the conversion of water vapor or other gas to liquid sate as the temperature drops or atmospheric pressure rises. (Also see Dew Point)

Conductance, thermal: the thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature differences is established between the surfaces.

Conductor Head: a transition component between a through-wall scupper and downspout to collect and direct run-off water.

Contact Cements: adhesive used to adhere or bond various roofing components. These adhesives adhere mated components immediately on contract of surfaces to which the adhesive has been applied.

Coping: the covering piece on top of a wall which is exposed to the weather, usually made of metal, masonry or stone. It is preferably sloped o shed water back onto the roof.

Copolymer: the product of polymerization of two or more substances at the same time; a "mixed" polymer.

Copolymerization: a chemical reaction that results in the bonding of two or more dissimilar monomers to produce large, long-chain molecules which are copolymers.

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.

Counterflashing: formed metal sheeting secured on or into a wall, curb, pipe, rooftop unit or other surface, to cover and protect the upper edge for the membrane base flashing or underlying metal flashing and associated fasteners from exposure to the weather.

Course: (1) the term used for each row of shingles of roofing material that forms the roofing, waterproofing or flashing system; (2) on layer of a series of materials applied to a surface (e.g., a five-course wall flashing is composed of three applications of roof cement with one ply of felt or fabric sandwiched between each layer of room cement.)

Cover Plate: a metal strip sometimes installed over the joint between formed metal pieces.

Coverage: the surface area covered by a specific quantity of a particular material.

CPA: copolymer alloy

CPE: chlorinated polyethylene

Crack: a non-linear separation or fracture occurring in a material. May be generally caused by induced stress, dimensional instability or substrate movement. Some cracks may be more of a linear separation or fracture. (See Split.)

Creep: the permanent deformation of a roofing material or roof system caused by movement of the roof membrane or compression of a a roof insulation board at fastener positions, that results from continuous load or thermal stress or loading. Creep at roof temperature is sometimes called "cold flow."

Cricket: an elevated roof substrate or structure, constructed to divert water around a chimney, curb, away from a wall, expansion joint or other projection/penetration. (See Saddle).

Crosslinking: the formation of chemical bonds between polymeric chains to yield an insoluble, three dimensional polymeric structure. Crosslinking of rubber is referred to as vulcanization or "curing."

CRREL: Cold Regions Research and Engineering Laboratory

CSI: Construction Specification Institute

CSM: L ASTM designation for chlorosulfonated polyethylene. (See CSPE.)

CSPE: Chlorinated polyethylene.

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.

Cure: a process whereby a material is caused to form permanent molecular linkages by exposure to chemicals, heat , pressure and/or weathering.

Cured Concrete: concrete that has attained its intended design performance properties.

Cutback: solvent-thinned bitumen used in cold-applied ("process:) roofing adhesives, roof cements and roof coatings.
Cutoff: a permanent detail designed to seal and prevent lateral water movement in an isolation system, and used to isolate sections of a roofing system. (Note: a cutoff is different form a tie- off, which may be a temporary or permanent seal.) (See Tie-off.)

Cutout: the open portion of a strip shingle between the tabs.

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D

Dampproofing: treatment of a surface or structure to resist the passage of water in the absence of hydrostatic pressure.

Dead Level: essentially horizontal or flat, as in a roof deck or rooftop with no intentional slope to the roof drains. Also referred to as zero (0) slope. (See Slope)

Dead-Level Asphalt: (See Asphalt)

Dead Loads: permanent non-moving loads that result from the weight of a building's structural and architectural components, mechanical and electrical equipment, and the roof assembly itself. Essentially the same as "dead weight" or "dead weight loads".

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. Decks ar either non-combustible (e.g., corrugated metal, Concrete or gypsum) or combustible (e.g., wood plank or plywood). and provide the substrate to which the roofing or waterproofing system is applied.

Deflection (Bowing, Sagging): the downward displacement of a structural member or system under load.

Degradation: a deleterious change in the chemical structure, physical properties or appearance of a material due to natural or artificial exposure (e.g., exposure to radiation, moisture, heat, freezing, wind, ozone, oxygen, etc.).

Degree Days: the difference between a reference temperature (usually 65 degree F, 18.3 degree C) and the mean temperature for the day, times 24 hours, times the number of day in the period. Degree days are used to compare the severity of cold or heat during the heating or cooling season.

Delamination: separation of the laminated layers of a component or system.

Design Loads: those loads specified in building codes or standards published by federal, state, county or city agencies or in owners' specification to be used in the design of a building.

Dew Point Temperature: the temperature at which water vapor condense in cooling air at the existing atmospheric pressure and vapor content. Cooling at or below the dew point will cause condensation.

Diaphragm: (See Roof Diaphragm.)

Dimensional Stability: the ability of a material to resist change in length and/or width and/or thickness that results from exposure to elevated or freezing temperatures, and moisture, overtime.

DOE: Department of Energy

Double Graveling: the process of applying tow layers of flood coats of bitumen and aggregate to a built-up roof. Loose aggregate should be swept from the first application prior to the second casting of bitumen and aggregate. Approximately 50% of the second aggregate application will remain adhered in the bitumen flood coat unless physically removed.

Downspout: a conduit used to carry runoff water form a scupper, conductor head or gutter of a building to lower roof level or to the ground or storm water runoff system.

Drain: an outlet or other device used to collect and direct the flow of runoff water from a roof area. (See NRCA Construction Detail "w-1".)

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. A drip edge also can be used to break the continuity of contact between the roof perimeter and wall components to help prevent capillary action.

Dynamic Load: any load which is nonstatic, such as a wind load or a moving live load.

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E

Eave: a projecting edge of a roof that extends beyond the supporting wall.

Eave Height: the vertical dimension from finished grade to the eave.

ECH: polyepichlorohydrin, commonly referred to as epichlorohydrin.

Edge Stripping: membrane flashing strips cut to specific widths used to seal/flash perimeter edge metal and the roof membrane.

Edge Venting: the practice of providing regularly spaced or continuously protected (e.g., louvered ) openings along a roof edge or perimeter, used as part of a ventilation system to dissipate heat and moisture vapor.

Efflorescence: the formulation of crystalline deposits, generally whitish in color, on the surface of stone, brick, concrete or other masonry surface when moisture moves through and evaporates on the masonry. May also be caused by free alkalies leached fromm mortar, grout or adjacent concrete.

EIP: Ethylene Inter Polymer

Elasticity: the property of matter by virtue of which it tends to return to its original size and shape after removal of a stress or force which caused a deformation.

Elastomer: natural or synthetic material which, at room temperature, can be stretched under low stress and, upon immediate released of the stress or force, will return quickly to its approximate original dimensions.

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.

Electrolyte: a liquid, most often a solution, that will conduct current.

Elongation: the ability of a material (e.g., roofing membrane) to be stretch by the application of a force.

Embedment: (1) the process installing or pressing-in a reinforcement felt, fabric, mat or panel uniformly into bitumen or adhesive; (2) the process of pressing granules into coating during the manufacture of factory-prepared roofing; (3) the process whereby ply sheet, aggregate or other roofing components settle into hot or cold-applied bitumen via the force of gravity.

Embrittlement: the loss of flexibility or elasticity of a material. The transition of a flexible material to a brittle state.

Emulsion: a dispersion of fine particle or globules in a liquid.
(See Asphalt Emulsion and Bitumen Emulsion)

End Lap: the distance of overlap where one ply, panel or piece extends beyond the end of the immediately adjacent underlying ply, panel or piece.

Envelope: (Bitumen-stop): a continuous edge seal formed at the perimeter and at penetrations by extending the base sheet or one ply of felt beyond the edge of the membrane field plies. After all overlying field plies or insulation are in place, the extended ply is turned back onto the membrane and adhered. THe envelope is intended to prevent bitumen seepage from the edge of the membrane.

EPDM: Ethylene Propylene Diene Monomer (See also Ethylene Propylene Diene Terpolymer.)

Epichlorohydrin(ECH): a synthetic rubber including two epichlorohydrin based elastomers. It is similar to and compatible with EPDM. ECH is typically used in lieu of EPDM when enhanced resistance to animal fat is needed.

Epoxy: a class of synthetic, thermosetting resins that produce tough, hard, chemical-resistant coating and adhesives.

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; (2) the typical moisture content of a material in any given geographical area.

Equiviscous Temperature (EVT): the temperature at which a bitumen attains the proper viscosity for built-up membrane application.

Equiviscous Temperature (EVT) Application Range: the recommended bitumen application temperature range. The range is approximately 25 degree F (14 Degrees C) above or below the EVT, thus giving a range of approximately 50 degree F (28 degrees C). The EVT Range Temperature is measured in the mop cart or mechanical spreader just prior to application of the bitumen to the substrate.

Equiviscous Temperature (EVT) for Asphalt: the recommended EVT for roofing asphalt (ASTM D312, Type I, II, III, or IV) is as follows:

Mop Application: the temperature at which the asphalt's apparent viscosity is 125 centipoise (0.458 Pa s).

Mechanical Spreader Application: the temperature at which the asphalt's apparent viscosity is 75 centipoise (.075 Pa s).

Note: if there are simultaneous mop and mechanical spreader applications, in order to avoid the use of two kettles, the EVT for mechanical spreader application may be used for both application techniques.

Equiviscous Temperature (EVT) for Coal Tar: the recommended EVT for roofing coal tar (ASTM D450, Type I or III) is the temperature at which the coal tar's apparent viscosity is 25 centipoise (0.025 Pa s).


Ethylene Interpolymers (EIP): a group of thermoplastic compounds generally based on PVC polymers from which certain single-ply roofing membranes can be formulated.

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.

EVT: Equiviscous Temperature

Exhaust Ventilation: air that is typically vented or exhausted from the roof cavity, typically through vents installed on the upslope portion of the roof. For example, with most steep-slope roof assemblies exhaust vents are typically located at or near the ridge.

Expansion Joint: a structural separation between two building elements that allows free movement between the elements without damage to the roofing or waterproofing system.

Extrusion: a manufacturing process which consists of forcing batched and formulated material (which may be molten ) through an orifice called a "die." The shape and dimensions of the orifice determine the shape and dimensions of the finished product. Extrusion is one method by which some single-ply roofing membranes are manufactured.

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F

Fabric: a woven cloth or material of organic or inorganic filaments, threads or yarns used for reinforcement in certain membranes and flashings.

Factory Mutual Research Corporation (FMRC) (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 companies in THE United States.

Factory Seam: a splice/seam made by the manufacturer during the assembly of sections of materials into large sheets.

Fallback: a reduction in the softening point temperature of asphalt that occurs when asphalt is heated for prolonged periods at elevated temperature. (See Softening Point Drift).

Fascia: a vertical of steeply sloped roof or tim located at the perimeter of a building. Typically it is border for the low-slope roof system that waterproofs the interior portions of the building.

Fasteners: any of a wide variety of mechanical securement devices and assemblies, including nails, screws, cleats, clips, and bolts, which may be used to secure various components of a roof assembly.

Felt: a flexible sheet manufactured by the interlocking of fibers through a combination of mechanical work, moisture and heat. Roofing felts may be manufactured principally form wood pulp and vegetable fibers (organic felts), asbestos fibers (asbestos felts), glass fibers (fiberglass felts or plysheet) or polyester fibers.

Felt Machine (Felt Layer): a mechanical device used for applying bitumen and roofing felt or plysheet simultaneously.

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.

Field of the Roof: the central or main portion of a roof, excluding the perimeter and flashing.

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. Film: a membrane or sheeting having nominal thickness not greater than 10 mils.

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.

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 materiel and membranes to prevent sticking.

Fishmouth (also referred to as and 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 plysheets during installation; (2) in shingles, a half-conical opening formed at a cut edge.

Flaking: detachment of a uniform layer of coating or surface material, usually related to internal movement, lack of adhesion or passage of moisture.

Flame Spread: Per ASTM E84, a measure of relative combustibility. The flame spread of a tested material is rated relative to Asbestos cement board (flame spread =0) and red oak flooring (flame spread=100).

Flammability: the characteristic of a material to burn or support combustion.

Flange: the projecting edge of a rigid or semi-rigid component, such as metal edge flashing flange, skylight flange, flashing boot, structural member, etc.

Flashing: components used to weatherproof or seal the roof system edges at perimeters, penetrations, wall, expansion joints, valley, drains, and other places where the roof covering is interrupted or terminated. For example, membrane base flashing covers the edge of the field membrane, and cap flashings or counterflashings shield the upper edges of the base flashing.

Flashing Cement: as used by the roofing industry, an ASTM D 2822 Type II roof cement that is 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 indicates it is intended for use on vertical surfaces. (See Asphalt Roof Cement and Plastic Cement.)

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.

Fleece: mats or felts composed of fibers (usually non-woven polyester fibers), often used as membrane backer.

Flood (Pour) Coat: the surfacing layer of bitumen into which surfacing aggregate is embedded on an aggregate-surfaced built-up roof. A flood coat is generally thicker and heavier than a glaze coat, and is applied at a proximately 45-60 pounds per square (2-3 Kilograms per meter).

Flood Test: the procedure where a controlled amount of water is temporarily retained over a horizontal surface to determine the effectiveness of the waterproofing.

Fluid-Applied Elastomer: a liquid elastomeric material that cures after application to form a continuous waterproofing membrane.

FM: (See Factory Mutual Research Corporation.)

Force: an action that changes or tends to change the state of rest or motion.

FPL: Forest Products Laboratory

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.

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G

G-90: a typical coating weight for galvanized metal sheet. Equates to 0.90oz. (26g) of zinc per sq. ft., measured on both sides Gable: a triangular portion of the endwall of a building directly under the slope roof and above the eave line.

Gable-shaped Roof: a single-ridge roof that terminates a gable end(s).

Galvanic Action: an electroylic reaction between dissimilar metals in the presence of and electrolyte.

Galvanized Steel: steel coated with zinc for corrosion resistance.

Gauge: a measurement of metal thickness.

Glass Felt: a sheet composed of bonded glass fibers, suitable for impregnation and coating in the manufacture of bituminous roofing and waterproofing materials and shingles.

Glass Mat: a thin mat composed of glass fibers, woven or non-woven, with or without a binder. This mat may serve as reinforcement for certain roof materials and membranes.

Glaze Coat: (1) the top layer of asphalt on a smooth-surface built-up roof membrane; (2) a thin protective coating of bitumen applied to the lower plies or to ply or a built-up roof membrane when application of additional felts or the flood coat and aggregate surfacing are delayed. (Also see Flood Coat.)

Grain: a unit used to measure the mass of moisture.

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.

Gravel: aggregate resulting from the natural erosion of rock.

Gravel Stop: a low profile upward-projecting metal edge flashing with a flange along the roof side, usually formed from sheet or extruded metal. Installed along the perimeter of a roof to provide a continuous finished edge for roofing material. Acts as a bitumen-stop during mop application of hot bitumen along a perimeter edge.

Groundwater Level: at a particular site, the level below which the subsoil and rock masses of the earth are fully saturated with water.

Grout: a mixture of cement, sand, and water used to fill pitch-pans/pockets, prior to the application of a pourable sealer.

Gutter: a channeled component installed along the downslope perimeter of a roof to convey runoff water form the roof to the drain leaders or downspouts.

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H

Headlap: the distance of overlap measured from the uppermost ply or course to the point that it laps over the undermost ply or course.

Heat Aging: controlled exposure of materials to elevated temperatures overt time.

Heat Seaming (see Heat Welding): the process of joining thermoplastic films, membranes of sheets by heating and then applying pressure to bring both materials in contact with each other.

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.

Heat Welding (see Heat Seaming): method of melting and fusing together the overlapping edges of separate sections of thermoplastic or uncured elastomeric roofing membranes by the application of heat (in the form of hot-air or open flame) and pressure.

Hip: the inclined external angle formed by the intersection of two sloping roof planes.

Hip Roof: a roof that rises by inclined planes for all four sides of a square or rectangular shaped building.

Hoist: a mechanical lifting device.

Holiday: an area where a liquid applied material is missing or absent.

"Hot" or "Hot Stuff": the roofer's term for hot bitumen.

Humidity: the amount of moisture contained in the atmosphere. Generally expressed as percent relative humidity (the ratio of the amount of moisture [water vapor] actually present in the air, compared to the maximum amount that the air could contain at the same temperature.

HVAC: heating, ventilating, and air conditioning equipment.

Hydrocarbon: an organic chemical compound primarily containing the elements carbon and hydrogen.

Hygroscopic: the property of a material to attract, absorb, and retain atmospheric moisture.

Hypalon: a registered trademark of E.I. duPont de Nemours, Inc., for "Chlorinated polyethylene" (CSPE). (See Chlorinated polyethylene.)

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I

ICBO: International Conference of Building Officials. Author of The Uniform Building Code.

Ice Dam: a mass of ice formed at the transition from a warm to cold roof surface, frequently formed by refreezing meltwater at the overhang of a steep roof, causing ice and water to back up under roofing materials.

Impact Resistance: the ability to a roofing material to resist damage (e.g., puncturing) from falling objects, application equipment, foot traffic, etc. The impact resistance of the roofing assembly is function of all its components, not just the membrane itself.

Impregnate: to coat, saturate, and/or surround the fibers of a reinforcing mat or fabric with an enveloping liquid material, (e.g., bitumen, elastomeric compound, etc.).

Incline: the slope of a roof expressed either in percent or in the number of vertical units of rise per horizontal units of run. (Also see Slope.)

Infrared Thermography: a practice of roof system analysis where an infrared camera is used to measure the temperature differential of a roof surface to locate areas of underlying wet or moist insulation. (See Thermal Image).

Inorganic: any chemical or compound that is derived from mineral, does not contain carbon, and is not classified as organic; being or composed of materials other than hydrocarbons and their derivatives; not for plants or animal origin.

Insect Screen: wire mesh used to prevent insects form entering the building through ventilators, louver or other openings.

Insulation: any of a variety of materials designed to reduce the flow of heat, either form or into a building. (See also Thermal Insulation.)
Intake Ventilation: the fresh air that is drawn into a passive ventilation system through vents typically installed in the soffit or eave of a roof.

Interlayment: a felt, metal or membrane sheet material used between courses of steep-slope roofing to improve the weather- and water shedding characteristics of the primary roof covering during times of wind-driven rain and snow. Typically used with wood shakes.

Internal Pressure: pressure inside a building that is a function of ventilating equipment, wind velocity, and the number and location of openings and air leaks.

Inverted Roof Membrane Assembly (IRMA): a patented, proprietary variation of the "Protected Membrane Roof Assembly" in which Styrofoam Brand Insulation and ballast are placed over the roof membrane. IRMA and Styrofoam are registered trademarks of the Dow Chemical Company.

IRWC: Institute of Roofing and Waterproofing Consultants

ISANTA: International Staple, Nail & Tool Association

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J

Joist: any of the small timbers, metal or wood beams arranged parallel from wall to wall to support a floor, ceiling or roof of a building.

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K

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.

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L

Laitance: a layer of weak nondurable material containing cement and fines from aggregates, brought by bleeding water to the top of overwet concrete. Laitance may be detected by scraping the concrete surface with a putty knife; if a quantity of loose powdery material is observed or easily removed, excessive laitance may be considered to be present.

Laminate: to bond two or more layers of a material together to make a finished product.

Lap: that part of a roofing, waterproofing or flashing component that overlaps or covers may portion of the same or another type of adjacent component.

Lap Seam: occurs where overlapping materials are seamed, sealed or otherwise bonded.

Lead: a soft workable metal used for miscellaneous flashings.

Leader Head: (See Conductor Head)

Life Cycling Costing: a method of economic analysis that takes into account expected costs over the useful life of an asset.

Light Reflectance: the percentage of light that is not absorbed by the surface of a material.

Live Loads: temporary loads that the roof structure must be designed to support, as required by governing building codes. Live loads are generally moving and/or dynamic or environmental, (e.g., people, installation equipment, wind, snow, ice or rain, etc.).

Loose-Laid Membranes: membranes that are not attached to the substrate except at the perimeter of the roof and at penetrations. Typically, loosed-laid membranes are held in place with ballast, such as water worn stone, gravel, pavers, etc.

Low Temperature Flexibility: the ability of a membrane or other material to remain flexible (resist cracking when flexed), after it has been cooled to a low temperature.

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M

Mansard: a decorative steep sloped roof on the perimeter of the building.

Mansard Roof: a steeper roof that terminates into a flat roof at its high point.

Masonry: anything constructed of such materials as bricks, stone, concrete blocks, ceramic blocks or concrete.
Mastic: (See Asphalt Roof Cement).

Mat: a thin layer of woven, non-woven or knitted fiber that serves as reinforcement to the material or membrane.

Material Safety Data Sheets: a written description of the chemicals within a product, and pertinent other data including such things as safe handling and emergency procedures. In accordance with OSHA regulations, it is the manufacturer's responsibility to produce an MSDS and the employer's responsibility to communicate its contents to employees.

MBDA: Systems Builders Association (formerly Metal Builders Dealers Association)

MBMA: Metal Building Manufactures Association

MCA: Metal Construction Association

Mechanically-Fastened Membranes: generally used to described membranes that have been attached defined intervals to the substrate. Mechanical fastening may be performed with various Fasteners and/or other mechanical devices, such as plates of battens.

Membrane: a flexible or semi-flexible material, which functions as the waterproofing component in a roofing or waterproofing assembly, and whose primary function is the exclusion of water.

Metal Film: a layer of foil made from a single metallic substance or from and alloy, that is laminated to a membrane during manufacture. The metal foil serves as the weathering surface of the membrane or flashing material.

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)

Meter: unit of length measurement in the metric system, equal to 39.37 inches.

Mica Dust: crystallized complex silicate minerals that are pulverized into dust form for use as a release agent. (See Talc)

Microbiological Resistance: the ability of a material to resist attack and degradation by various air and soil-borne micro-organisms.

MIL: a unit of measure, one mil is equal to 0.001 inches or 25.400 microns, often used to indicate the thickness of a roofing membrane.

Millimeter: a unit of measure equal to one thousandth (0.001) of a meter or 0.03937 inches.

MIMA: Mineral Insulation Manufacturers Association

Mineral Fiber: inorganic fibers of glass, asbestos or rock (mineral wool).

Mineral Granules: (See Granules)

Mineral Stabilizer: a fine, water-insoluble inorganic material, used ina mixture with solid or semi-solid bituminous materials.

Mineral-Surfaced Roofing: roofing materials whose surface or top layer consists of mineral granules.

Mineral-Surfaced Sheet: a roofing sheet that is coated on one or both sides with asphalt and surfaced with mineral granules.

Model Codes: a compilation of standards or codes established to provide uniformity in regulations pertaining to building construction. Examples: ICBO (International Conference of Building Officials); BOCA (Building Officials and Code Administration); SBC (Standard Building Code)

Modified Bitumen: (1) a bitumen modified through the inclusion of one or more polymers (e.g., atactic polypropylene, styrene butadiene styrene, etc.); (2) composite sheets consisting of a polymer modified bitumen often reinforced and sometimes surfaced with various types of mats, films, foils and mineral granules.

Moisture Contour Map: a map used to graphically define the location of moisture within a roof assembly after a moisture scan has been performed.

Moisture Relief Vent: a venting device installed through the roofing membrane to relieve moisture vapor pressure from within the roofing system.

Moisture Scan: the use of mechanical device (capitance, infrared or nuclear) to detect the presence of moisture within a roof assembly. (see Non-Destructive Testing)

Mole Run: a meandering buckle or ridging in a roof membrane not associated with insulation or deck joints.

Monomer: a simple molecule that is capable of combining with a number of like or unlike molecules to form a polymer.

Mop-and-Flop: an application procedure in which roofing elements (insulation boards, felt plies, cap sheets, etc.) are initially place upside down adjacent to their ultimate locations, are coated with adhesive or bitumen, and are then turned over and applied to the substrate.

Mopping: the application of hot bitumen, with a roofer's hand mop or mechanical applicator, to the felts of a bituminous membrane.

Solid Mopping: a continuous mopping of a surface.

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.

Sprinkle Mopping: a random mopping pattern in which heated bitumen beads are strewn onto the surface with a brush or mop.

Strip Mopping: a mopping pattern in which hot bitumen is applied in parallel bands.

Mud Cracking: surface cracking of a material whereby the degraded material appears similar to dried, cracked earthen mud.

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N

NAHB: National Association of Home Builders

Nailer (commonly 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. Generally, it is recommended that nailers be the same thickness as the adjacent insulation, and may be treated with non-oil borne preservative, and be sufficient width to fully support the horizontal flashing flange of a metal flashing (where used)

Nailing: the application of nails. May be: (1) exposed nailing of a roofing wherein nail heads are exposed to the weather; (2) concealed nailing of a roofing wherein nail heads are concealed from the weather by an overlapping material.

NBP: acrylonitrile butadiene polymer blend. One proprietary NBP membrane is commonly referred to as nitrile butadiene copolymer.

Needle Punched Fabric: a fabric where barbed needles (in multiple punches) achieve mechanical bonding or interlocking of fibers

Neoprene: synthetic rubber (polychloroprene) used in liquid-applied and sheet applied elastomeric roof membranes or flashings.

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.

Newton (N): is unit of measure for force.

NICA: National Insulation Contractors Association

Night Seal (or Night Tie-off): 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.

Nineteen-Inch Selvage: ("Double-Coverage or Split-Sheet"): a prepared roofing sheet with a 17 inch (430mm) granule surfaced exposure and a non-granule surfaced 19 inch (485mm) selvage edge. This material is sometimes referred to as SIS, double-coverage or according to ASTM Standard D371-89, Standard Specification for Asphalt Roll Roofing (Organic Felt) Surfaced with Mineral Granules; Wide Selvage.

Ninety-Pound: a prepared organic felt roll-roofing with a granule surfacing that has a mass of approximately 90 pounds per 100 square feet. (4400g/m2).

NIST: National Institute of Standards and Technology

Nitrile Alloy: and elastomeric material of synthetic non-vulcanizing polymers.

Nitrile Rubber: a membrane whose predominant resinous ingredient is a synthetic rubber made by the polymerization of acrylonitrile with butadiene.

Non-Destructive Testing (NDT): a method to evaluate the disposition, strength or composition of materials without damaging the object under test. Typically used to evaluate moisture content in roofing assemblies, the three common test methods are electrical capacitance, infrared thermography, and nuclear back-scatter.

Non-Vulcanized Membrane: a membrane manufactured from thermoplastic compounds that retains its thermoplastic properties throughout the service life of the membrane.

Nonwoven: a term used to describe fabrics, mats or scrims that are produced using processes other than weaving or knitting. Many nonwoven processes (i.e., spun-bonded or wet laid, etc.) produce a random arrangement of reinforcing fibers (glass, polyester, etc.) in a mat or fabric.

NRCA: National Roofing Contractors Association

NTRMA: National Tile Roofing Manufacturers Association

Nuclear Testing (Nuclear back-Scatter): a device that contains a radioactive source to emit high velocity neutrons into a roof systems. reflecting neutrons are measured by a gauge this is used to detect moisture.

Nylon: generic name for a family of polyamide polymers, used as a scrim in some fabric reinforced sheeting.

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O

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.

Organic: being or composed of hydrocarbons or their derivatives originating from plant or animal matter.

Organic Felt: an asphalt roofing base material manufactured from cellulose fibers.

ORNL: Oak Ridge National Laboratory

Osmosis: the diffusion of fluids through a semi-permeable membrane or porous partition.

Ozone Resistance: the ability of a material to resist the deteriorating effects of ozone exposure.

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P

Parapet Wall: that part of a perimeter wall immediately adjacent to the roof which extends above the roof.

Partially-attached: a roofing assembly in which the membrane has been "spot affixed" to a substrate, usually with an adhesive or a mechanical device.

Pascal (N/m2): is unit of measure for force per unit area.

Peel Strength: the average force (or force per unit width) required to peel a membrane or other from the substrate to which it has been bonded.

Penetration: (1) any object passing through the roof; (2) the consistency (hardness) of a bituminous material expressed as the distance, in tenths of a millimeter (0.1mm), that a standard needle penetrates vertically into a sample of material under specified conditions of loading, time, and temperature.

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.

Perlite: an aggregate used in lightweight insulating concrete and in performed perlitic insulation boards, formed by heating and expanding siliceous volcanic glass.

Perm: a unit of water vapor transmission defined as 1 grain of water vapor per square foot per hour per inch of mercury pressure difference (1 inch of mercury=0.49 psi). the formula for perm is P= Grains of Water Vapor/Square Foot Hour Inch Mercury (P=grain in/ft_h in Hg [P=ng/(Pa s m)]).

Permeability: (1) the capacity of a porous material to conduct or transmit fluids; (2) the amount of a fluid moving through a barrier in a unit time, unit area and unit pressure gradient not normalized for, but directly related to thickness.

Permeance: the rate of water vapor transmission per unit area at a steady state through a material, membrane or assembly, expressed in Grain/Square Foot Hour Inch Mercury (grain/ft_h in Hg [ng/Pa a m_]).

Phased Application: the installation of sperate roof system or water proofing system component(s) during two or more sperate time intervals. Application of surfacings at different time intervals are typically not considered phased application. (See Surfacing) Picture Framing: a square or rectangular pattern of buckles or ridges in a roof covering generally coinciding with insulation or deck joints; generally, a function of movement of the substrate.

PIMA: Polyisocyanurate Insulation Manufacturers Association

Pinhole: a tiny hole in a coating, film, foil, membrane or laminate.

Pipe Boot: prefabricated flashing piece used to flash around circular pipe penetrations.

Pitch: (See Coal Tar, Incline, and Roof Slope)

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 seal the area around the penetration.

Plastic Cement: a roofing industry generic term used to describe Type 1 asphalt roof cement that is a trowelable mixture of solvent-based bitumen, mineral stabilizers, other fibers and/or fillers. Generally, intended for use on relatively low slopes-not vertical surfaces. (Also see Asphalt Roof Cement and Flashing Cement)

Plastic Film: a flexible sheet made by the extrusion of thermoplastic resins.

Plasticizer: a material, frequently solvent-like, incorporated in a plastic or a rubber to increase its ease of workability, flexibility or extensibility.

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.

Pliability: the material property of being flexible or moldable.

Ply: a layer of felt, plysheet or reinforcement in a roof membrane or roof system.

PMR: Protected Membrane Roof

Polychloroprene: (See Neoprene)

Polyester: a thermoplastic polymeric resin that is used to make a variety of materials and products. Polyester fibers are widely used as the reinforcing medium in certain membranes. (See polyester Fiber)

Polyester Fiber: a synthetic fiber usually formed by extrusion. Nonwoven fabrics, mats scrims made of polyester fiber are used for membrane reinforcement.

Polyisobutylene (PIB): a product formed by the polymerization of isobutylene. May be compounded for use as a roof membrane material.

Polymer: a natural or synthetic chemical compound of high molecular weight or a mixture of such compounds, formed when monomers (small individual molecules) are combined to form large long-chain molecules.

Polymer Modified Bitumen: see Modified Bitumen.

Polymerization: the process whereby monomers are combined to form large, chain-like molecules.

Polypropylene: a tough, lightweight plastic made by the polymerization of high-purity propylene gas.

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, fillers and other modifiers; rigid forms are used in pipes; flexible forms are used in the manufacture of sheeting and roof membrane materials.

Ponding: the excessive accumulation of water at low-lying areas on a roof.

Positive Drainage: the drainage condition is 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 ambient drying conditions.

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.

Press Brake: a machine used in cold-forming sheet metal or strips of metal into desired profiles.

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.

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 surfaces and increase the strength (in shear and peel) of the field splice.

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")

Puncture Resistance: extent to which a material is able to withstand the action of a sharp object without perforation.

Purlin: horizontal secondary structural member that transfers loads from the primary structural framing.

PVC: Polyvinyl Chloride

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R

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.

Rake: the sloped edge of a roof at or adjacent to the first or last rafter.

RCI: Roof Consultants Institute

RCMA: Roof Coatings Manufacturers Association

RDCA: Roof Deck Contractors Association

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

Reroofing: the process of re-covering or tearing-off and replacing an existing roof system.

Reflectivity: (See Light Reflectance)

Reglet: a sheet metal receiver for the attachment of counterflashing. (A reglet may be inset into a raggle, embedded behind cladding or a surface mounted.)

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 non-woven glass fibers, polyester mats or scrims, nylon or polyethylene sheeting.

Relative Humidity: the ration of the weight of moisture in a given volume of air vapor mixture to the saturated (maximum) weight of water vapor at the same temperature, expressed as a percentage. For example, if the weight of the moist air is 1 pound and if the air could hold 2 pounds of water vapor at the same temperature, the relative humidity (RH) is 50 percent.

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 removed for application of the shingles.

Replacement: the practice of removing an existing roof system down to the roof deck and replacing it with a new roofing system.

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=F h s ft2/Btu (R=K m2/W).

Ridge: highest point on the roof, represented by a horizontal line where two roof areas intersect, running the length of the area.

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.

Ridge Vent: one of many products located at the ridge that allows the escape of warm and/or moist air from the attic area or rafter cavity. Most ridge vents are either premanufactured metal or flexible shingle over.

Ridging: (See Buckle)

RIEI: Roofing Industry Educational Institute

RMA: Rubber Manufacturers Association

Roll Goods: a general term applied to rolls of roofing felt, plysheet, etc., which are typically furnished in rolls.

Roll Roofing: smooth-surfaced or mineral-surfaced, coated, prepared felts.

Roof Assembly: an assembly of interacting roof components (includes the roof deck, vapor retarder [if present], insulation, and roof covering).

Roof or Roofers' Cement: see Asphalt Roof Cement or Coal Tar Roof Cement.

Roof Covering: the exterior roof cover or skin of the roof assembly, consisting of membrane, panels, sheets, shingles, tiles, etc.

Roof Curb: raised frame used to mount mechanical units (such as air conditioning or exhaust fans), skylights, etc.

Roof Diaphragm: a structural roof deck that is capable of resisting shear that is produced by lateral forces, such as wind or seismic loads.

Roof Jack: a metal bracket used to support toe-boards on steep-slope roofs (Also see Flashing Collar)

Roof Overhang: a roof extension beyond the exterior wall of a building.

Roof Seamer: machine that crimps neighboring metal roof panels together or that welds laps of membrane sheets together using heat, solvent or dielectric energy.

Roof Slope: the angle a roof surface makes with the horizontal, expressed as a ration 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, slope may be expressed as a ration of rise to run, such as 4:12 or as a percent.)

Roof System: a system of interacting roof components, generally consisting of membrane or primary roof covering and insulation (not including the roof deck) designed to weatherproof and, sometimes, to improve the buildings' thermal resistance.

Roofer: craftsman who applies roofing materials.

Rosin Paper: a non-asphaltic paper used as a slip sheet in some roof systems.

Rubber: a polymeric material which, at roof temperature, is capable of recovering substantially in shape and size after removal of a force. May be natural or synthetic.

Run: horizontal dimension of a slope.

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S

Saddle: a relatively small raised substrate or structure constructed to channel or direct surface water to drains or off the roof. A saddle may be located between drains or in a valley, and is often constructed like a small hip roof or like a pyramid with a diamond shaped base. (See Cricket)

Saturated Felt: a felt that has been partially saturated with low softening point bitumen.

SBCCI: Southern Building Code Congress International, Inc.

SBS: (See Styrene Butadiene Styrene)

Scarfed: shaped by grinding.

Screeding: the process of striking off excess concrete to bring the top surface of the concrete to the proper finish and elevation.

Scrim: a woven, non-woven or knitted fabric, composed of continuous strands of material used for reinforcing or strengthening membranes. Scrim may be incorporated into a membrane by the laminating or coating process.

Scuttle: a hatch that provides access to the roof from the interior of the building.

SDI: Steel Deck Institute

Seal: (1) a generic term for function that prevents or controls the passage of water; (2) to secure a roof or structure from the entry of moisture.

Sealant: a single- or multi-component polymeric or bituminous-based material used to weatherproof many types of construction joints where moderate movement is expected. The material comes in various grades: pourable, self-leveling, non-sag, gun grade, and cured or uncured tapes.

Sealing Washer: a rubber or neoprene washer, sometimes metal-backed, typically assembled on a fastener to prevent water from migrating into and through the fastener hole.

Seam: a joint formed by mating two separate sections of material. Seams may be made or sealed in a variety of ways, including adhesive bonding, hot-air welding, solvent welding, using adhesive tape, sealant, etc.

Seam Strength: the force or stress required to separate or rupture a seam in the membrane material.

Self-Adhering Membrane: a membrane that can adhere to a substrate and to itself as 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 bonding to itself during shipping handling.

Self-Drilling Screw: a fastener that drills and taps its own hole during application.

Self-Tapping Screw: a fastener that forms receiving threads when turned into a previously drilled hole.

Self-Vulcanized Membrane: a membrane manufactured from compounds that are thermoplastic during manufacture and installation, but whose polymers eventually crosslink and cure during exposure.

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, such as overlapping or seaming.

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 obtain better adhesion of the overlapping sheet.

Shark Fin: an upward-curled felt side lap or end lap.

Shear Strength: (in roofing) the stress required to disrupt a seam or bonded joint or attachment by forcing the substrate material to slide out from the overlying material or vice versa.

Shed Roof: a roof containing only one sloping plane. Has no hips, ridges or valleys.

Sheet Metal Flashing: (See Metal Flashing)

SI: the international symbol for the metric unit (Le Systeme International d'Unites). Side Lap: the continuous longitudinal overlap of neighboring like materials.

Side Lap Fastener: a fastener used to connect adjacent panels together at the side lap.

Sieve: an apparatus with uniform sized openings for separating sizes of material.

Silicone-Based Water Repellents: any of the organopolysiloxanes (silicone derivative) applied to masonry materials for dampproofing or repelling water.

Sill: the bottom horizontal framing member of an opening, such as below a window or door.

Single Coverage: roofing material that provides one layer over the substrate to which it is applied.

Single-Ply Membranes: roofing membranes that are field applied using just one layer of membrane material (either homogeneous or composite) rather than multiple layers.

Single-Ply Roofing: a roofing system in which the principal roof covering is a single layer flexible membrane, often of thermoset, thermoplastic or polymer modified bituminous compounds.

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 and (6) Self-adhering.

Skylight: a roof accessory, set over an opening in the roof, designed to admit light. Normally transparent, and mounted on a raised framed curb.

Slag: a hard, air cooled 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.

Slip Sheet: sheet material, such a 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 between them, and to prevent possible damage from chemical incompatibility, wearing or abrasion of the membrane.

Slope: the angle of incline, usually expressed as a ration of rise to run or as a percent. (See Roof Slope)

SMACNA: Sheet Metal and Air Conditioning Contractors National Association

Smooth Surfaced Roof: a roof membrane without mineral granule or aggregate surfacing.

Snow Load: a load imposed on buildings or other structures due to snowfall. (Categorized as live or environmental load.)

Soffit: the enclosed underside of any exterior overhanging section of a roof eave.

Soffit Vent: a premanufactured or custom built air inlet source located at the downslope eave or in the soffit of a roof assembly.

Softening Point: the temperature at which bitumen becomes soft enough to flow, as determined by a closely defined method (ASTM Standard test method D 36 or D 3461).

Softening Point Drift: a change in the softening point of bitumen (See Fallback)

Soil Stack: a sanitation pipe that penetrates the roof; used to vent plumbing fixtures.

Solid Mopping: (See Mopping)

Solvent: liquid used to dissolve or disperse film-forming constituents, and which evaporates during drying and does not become a part of the dried film.

Solvent Cleaners: used to clean some single-ply roofing membranes prior to splicing, typically including heptane, hexane, white gasoline, and unleaded gasoline.

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).

Spalling: a condition in which the outer layer or layers of masonry or concrete material begin to break off or flake away.

Special Steep Asphalt: Type IV Asphalt (See Asphalt)

Specification: a statement of requirements for a given job or project. Usually describes products, materials, and processes to be used. A specification may also contain terms of the contract.

SPI: The Society of The Plastics Industry

Splice: bonding or joining of overlapping materials. (See Seam)

Splice Plate: a metal plate placed underneath the joint between two pieces of metal.

Splice-Tape: cured or uncured synthetic rubber tape used for splicing membrane materials.

Split: a rupture (generally linear) or tear in a material or membrane resulting from tensile forces.

Split Sheet: (See Nineteen-inch Selvage)

Spot Mopping: (See Mopping)

Spread Coating: a manufacturing process in which membranes are formed using a liquid compound, prepared in mixers and then fed to individual coaters. The mixture is spread onto a supporting reinforcement base layer. After coating, the material passes through a channel causing it to change from a paste to a solid membrane, in sheet form.

SPRI: Single Ply Roofing Institute

Sprinkle Mopping: (See Mopping)

Spunbond: a type of nonwoven fabric formed from continuous fiber filaments that are laid down and bonded continuously, without an intermediate step.

Spunlaced: a nonwoven fabric made by mechanically bonding a dry-laid staple fabric by water jet, which entangles the individual fibers.

Square: 100 square feet (9.29m2) of roof area.

Stainless Steel: and alloy of steel that contains a high percentage of chromium. Also may contain nickel or copper. Generally, has very good resistance to corrosion.

Standing Seam: a metal roof system that consists of an overlapping or interlocking seam that occurs at an upturned rib. The standing seam may be made by turning up the edges of two adjacent metal panels and overlapping them, then folding or interlocking them in a variety of ways.

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.

Starter Sheets: (1) felt, plysheet or membrane strips that are made or cut to widths narrower than the standard width of the roll, used to start the shingling pattern at an edge of the roof; (2) particular width sheets designed for perimeters in some mechanically attached and fully adhered single-ply systems.

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.

Steep Asphalt: Type III Asphalt (See Asphalt)

Step Flashing: individual pieces of 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.

Strain: the dimensionless expression for the elongation of a material under stress. Strain is expressed as the ratio of elongation per unit length.

Strapping (felts): a method of installing roofing rolls or sheet good materials parallel with the slope of the roof.

Stress: the internal resistance of a material to a force, measured as a force per unit area.

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 scrim or reinforcement.

Strip Mopping: (See Mopping)

Strip Shingles: asphalt shingles that are manufactured in strips, approximately three times as long as they are wide.

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 installation.

Stripping or Strip-Flashing: membrane flashing strips used for sealing or flashing metal flashing flanges into the roof membrane.

Stripping-In: application of membrane stripping ply or plies.

Styrene Butadiene Rubber: high molecular weight polymers having rubber-like properties, formed by the random copolymerization of styrene and butadiene monomers.

Styrene Butadiene Styrene Copolymer (SBS): high molecular weight polymers that have both thermoset and thermoplastic properties, formed by the block copolymerization of styrene and butadiene monomers. These polymers are used as the modifying compound in SBS polymer modified asphalt roofing membranes to impart rubber-like qualities to the asphalt.

Substrate: the surface upon which the roofing or waterproofing membrane is applied (e.g., in roofing, the structural deck or insulation).

Sump: an intentional depression around a roof drain or scupper that serves to promote damage.

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.

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).

Surface Cure: curing or vulcanization that occurs in a thin layer on the surface of a manufactured polymeric sheet or other items.

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 sheet. Additional details of this procedure may be found in ASTM D 4263.

Surfacing: the top layer or layers of a roof covering, specified or designed to protect the underlying roofing from direct exposure to the weather.

SWRI: Sealant, Waterproofing and Restoration Institute

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.

Systems Builders Association: SBA

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T

Tab: the exposed portion of strip shingles defined by cutouts.

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.

Tapered Edge Strip: a tapered insulation strip used to (1) elevate and slope the roof at the perimeter and at curbs, and (2) provide a gradual transition from one layer of insulation to another.

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.

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.

Tar Boils: bubbles of moisture vapor encased in a thin film of bitumen, also known as "blackberries."

Tarred Felt: (See Coal Tar Felt)

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).

Tear Strength: the maximum force required to tear a specimen.

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.

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.

Tensile Strength: the maximum force (longitudinal pulling stress) a material can bear without tearing or breaking apart.

Tensile Test: a test in which a specimen is subjected to increasing longitudinal pulling stress until fracture occurs.

Termination: the treatment or method of anchoring and/or sealing the free edges of the membrane in a roofing or waterproofing system.

Terne: an alloy of lead and tin, used to coat sheets of carbon or stainless steel for use as metal roofing sheet.

Terra Cotta:low-fired clay, either glazed or unglazed.

Test Cut: a sample of the roof, which may contain all components or just the membrane, usually used to diagnose the condition of the exiting membrane, evaluate the type and number of plies or number of membranes or rates of application such as determine the weight of the average interply bitumen moppings.

Thatch Roof: the covering of a roof usually made of straw, reed or natural foliage (palms) bound together to shed water.

Therm: a unit of heat equivalent to 100,000 BTU. Commonly used by utilities in quoting prices or costs.

Thermal Conductivity (k): the heat energy that will be transmitted by conduction through 1 square foot of 1 inch thick homogeneous material in one hour when there is a difference of 1 degree Fahrenheit perpendicularly across the two surfaces of the material. The formula for thermal conductivity is: k=Btu/Square Foot/Inch/Hour/Degree Fahrenheit

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.

Thermal Insulation: a material applied to reduce the flow of heat.

Thermal Resistance (R); an index of a material's resistance to heat flow; it is the reciprocal of thermal conductivity (k) or thermal conductance (C). The formula for thermal resistance is: R=1/C or. R=1/k or. R=Thickness in inches/k

Thermal Shock: the stress-producing phenomenon from sudden temperature changes in a roof membrane when, for example, a cold rain shower follows brilliant hot sunshine, which may result in sudden cooling or rapid contraction of the membrane.

Thermogram: a visible light record of the display of an infrared camera system via a Polaroid print, 35 mm film, video tape or computer generated image.

Thermography: a technique for producing heat "pictures" from the radiant energy emitted from stationary or moving objects without in any way influencing the temperatures of the objects under view. The electronic generation and display of a visible image of an infrared spectrum.

Thermoplastic: materials that soften when heated and harden when cooled. This process can be the objects under view. the electronic generation and display of a visible image of an infrared spectrum.

Thermoplastic Olefin Membrane (TPO): a blend of polypropylene and ethylenepropylene polymers. Colorant, flame retardants, UV absorbers and other proprietary substances which may be blended with the TOP to achieve the desired physical properties. The membrane may or may not be reinforced.

Thermoset: a material that solidifies or "sets" irreversibly when heated. This property is usually associated with crosslinking of the molecules induced by heat or radiation.

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.

Through-Wall Flashing: a water-resistant material, which may be metal or membrane, extending through a wall and its cavities, positioned to direct water entering the top of the wall or cavity to the exterior, usually through weep holes.

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 system.

TIMA: Thermal Insulation Manufacturers Association

Toggle Bolt: a two-piece assembly consisting of a thread bolt and an expanding clip that can fit through a drilled hole. The clip can spring outward to provide anchorage from the blind side.

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.

TPA: tri-polymer alloy

TPO: (See Thermoplastic Olefin)

Tuckpointing: the process of removing deteriorated mortar from an existing masonry joint and troweling new mortar or other filler into the joint.

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U

UBC: Uniform Building Code

UL: Underwriters Laboratories, Inc.

UL Label: an identification label or seal affixed to a roofing product