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Click on a letter to view the corresponding term:


APP: see Atactic Polypropylene.
Application Rate: the quantity (mass, volume, or thickness) of material applied per area.
Apron Flashing: a term used for a flashing located at the juncture of the top of the roof and a vertical wall or steeper-sloped roof.
Architectural Panel: a metal roof panel, typically a double standing seam or batten; usually requires solid decking underneath and relies on slope to shed water.
Architectural Shingle: shingle that provides a dimensional appearance.
ARMA: Asphalt Roofing Manufacturers Association
: a group of natural, fibrous, impure silicate materials used to reinforce some products.
Asphalt: a dark brown or black substance found in a natural state or, more commonly,as a residue after evaporating or otherwise processing crude oil or petroleum.may be further refined to conform to various roofing grade specifications:

Dead-Level Asphalt: a roofing asphalt conforming to the requirements of ASTMD 312,
Type I.
Flat Asphalt: a roofing asphalt conforming to the requirements of ASTMD 312, Type II.
Steep Asphalt: a roofing asphalt conforming to the requirements of ASTMD 312, Type III.
Special Steep Asphalt: a roofing asphalt conforming to the requirements of Specification D 312, Type IV.

Emulsion: a mixture of asphalt particles and an emulsifying agent such as clay and water.
components are combined by using a chemical or a clay emulsifying agent and/or blending machinery.

Bitumen: (1) a class of amorphous, black or dark colored, (solid, semi-solid, or) cementitious sub-stances, natural or manufactured, composed principally of molecular weight hydrocarbons, soluble in carbon disulfide, and found in asphalts, coal tars and pitches, wood tars and asphalts; (2) a generic term to denote any material composed principally of bitumen, typically asphalt or coal.
Bituminous Emulsion: a suspension of minute particles of bituminous material or other aqueous solution. (See Asphalt Emulsion.)
Bleed-Sheet: a sheet material used to prevent the migration of bitumen.
Blind-Nailing: the use of nails that are not exposed to the weather in the finished system.
Blister: an enclosed pocket of air, which may be mixed with water or solvent vapor, between impermeable layers of felt or membrane, or between the membrane and substrate.
Bond: the adhesive and/or cohesive forces holding two components in positive.
Bond, Chemical: adhesion between surfaces, usually of similar materials, resulting in a chemical reaction or cross-linking of polymer chains.
Bond, Mechanical: adhesion between surfaces resulting from interfacial forces or interlocking.
Bonding Agent: a chemical substance applied to a suitable substrate to create bonding and a succeeding layer.
Boot: (1) a covering made of flexible material, which may be preformed to a particular, used to exclude dust, dirt, moisture, etc. from around a penetration; (2) material used to form a closure, sometimes installed at inside and outside.
Bridging: (1) when the membrane is unsupported at a juncture; (2) bridging in slope roofing is a method of reroofing over standard-sized asphalt shingles with sized asphalt shingles.
Brooming: an action carried out to facilitate embedment of a ply of roofing material in hot bitumen by using a broom, squeegee, or special implement to smooth out and ensure contact with the bitumen or adhesive under the ply.
Buckle: an upward, elongated tenting displacement of a roof membrane frequently over insulation or deck joints. A buckle may be an indication of movement of the roof assembly.
Built-Up Roof Membrane (BUR): a continuous, semi-flexible multi-ply roof membrane, of plies or layers of saturated felts, coated felts, fabrics, or mats between alternate layers of bitumen are applied. Generally, built-up roof membranes are with mineral aggregate and bitumen, a liquid-applied coating, or a surfaced cap sheet.
Butt Joint: a joint formed by adjacent, separate sections of material, such as where neighboring pieces of insulation abut.
Butyl: rubber-like material produced by copolymerizing isobutylene with isoprene. Butyl may be manufactured in sheets, or blended with other materials to make sealants and adhesives.
Butyl Coating: an elastomeric coating system derived from polymerized isobutylene.coatings are characterized by low water vapor permeability.
Butyl Rubber: a synthetic elastomer based on isobutylene and a minor amount of. 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; also used to seal other types of sheet metal joints, and in various sealant.

Cant: a beveling of foam at a right angle joint for strength and water run off.
Strip: a beveled or triangular-shaped strip of wood, wood fiber, perlite, or other designed to serve as a gradual transitional plane between the horizontal 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 ofmembrane base flashing, wall flashing, or primary flashing. (See Flashing and.)
Cap Sheet: a granule-surface coated sheet used as the top ply of some built-up or bitumen roof membranes and/or flashing.
Capillary Action: the action that causes movement of liquids by surface tension when contact with two adjacent surfaces such as panel side laps.
Caulk: a material (usually a composition of vehicle and pigment) used for/sealing joints or junctures, where no elastomeric properties are required. (See.)
Caulking: (1) the physical process of sealing a joint or juncture; (2) sealing and weather-tight the joints, seams, or voids between adjacent units by filling with sealant.
Chalk: a powdery residue on the surface of a material.
Chalk Line: a line made on the roof by snapping a taut string or cord dusted with chalk. Used for alignment purposes.
Chalking: the degradation or migration of an ingredient, in paints, coatings, or other.
Chemical Resistance: the ability to withstand contact with specified chemicals without significant change in properties.
Chlorinated Polyethylene (CPE): a thermoplastic material, used for single-ply roof, composed of high molecular weight polyethylene which has been vulcanized; a process that yields a flexible rubber-like material.
Chlorosulfonated Polyethylene (CSPE or CSM): (probably best known by the DuPont name Hypalon TM ) a synthetic, rubber-like thermoset material, based on high weight polyethylene with suphonyl chloride, usually formulated to produce a vulcanizing membrane. Classified by ASTM Standard D 5019-89.
Clip: an individual (discrete) cleat. (See Cleat.
Coal Tar Roof Cement: a trowelable mixture of processed coal tar base, solvents, fillers and/or fibers. Classified by ASTM Standard D 4022 Coal Tar Roof.
Coated Base Sheet: a felt that has previously been saturated (filled or impregnated)asphalt and later coated with harder, more viscous asphalt, which greatly improves its impermeability to moisture.
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 installed at ambient or a slightly elevated temperature.
Concealed-Nail Method: a method of asphalt roll roofing application in which all nails driven into the underlying course of roofing and covered by an adhered course.
Coping: the covering piece on top of a wall which is exposed to the weather, usually of metal, masonry, or stone. It is preferably sloped to shed water back onto the.
Copper: a natural weathering metal used in metal roofing; typically used in 16 or 20per square foot thickness (4.87 or 6.10 kg/sq m).
Counterflashing: formed metal sheeting secured on or into a wall, curb, pipe, rooftop, or other surface, to cover and protect the upper edge of the membrane base or underlying metal flashing and associated fasteners from exposure to the.
Course: (1) the term used for each row of shingles of roofing material that forms the, 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 with one ply of felt or fabric sandwiched between each layer of roof cement.)
Cricket: an elevated roof substrate or structure, constructed to divert water around a, curb, away from a wall, expansion joint, or other projection/penetration. (See.)
Curb: (1) a raised member used to support roof penetrations, such as skylights, equipment, hatches, etc. above the level of the roof surface; (2) a raised perimeter relatively low in height.
Cure: a process whereby a material is caused to form permanent molecular linkages due toexposure to chemi-cals, heat, pressure, and/or weathering.
Cure Time: the time required to effect curing. The time required for a material to reach desirable long-term physical characteristics.

Dew Point Temperature: the temperature at which water vapor condenses in cooling at the existing atmospheric pressure and vapor content. Cooling at or below the point will cause condensation.
Double Coverage: application of asphalt, slate, or wood roofing such that the lapped is at least 2 inches (51mm) wider than the exposed portion, resulting in two layers of roofing material over the deck.
Double Lock Standing Seam: a standing seam that utilizes a double, overlapping between two seam panels. (See Standing Seam.)
Downspout: a conduit used to carry runoff water from a scupper, conductor head, or of a building to a 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 roof area.
Drip Edge: a metal flashing, or other overhanging component, with an outward lower edge, intended to control the direction of dripping water and help underlying building components. A drip edge also can be used to break the contact between the roof perimeter and wall components to help prevent action.
Dry-In or Dry-In Felt: usually the underlayment or the process of applying the felt for steep roofing.
Dynamic Load: any load which is nonstatic, such as a wind load or a moving live load.

Edge Stripping: membrane flashing strips cut to specific widths used to seal/flashedge 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 to dissipate heat and moisture vapor.
Elasticity: the property of matter by virtue of which it tends to return to its original sizeshape after removal of a stress or force which caused a deformation.
Elastomer: natural or synthetic material which, at room temperature, can be stretched low stress and, upon immediate release 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 and will return relatively quickly to its original shape when released.
Elastomeric Coating: a coating system which, when fully cured, is capable of being at least twice its original length (100% elongation) and recovering to its dimensions.
Embedment: (1) the process of installing or pressing-in a reinforcement felt, fabric,or panel uniformly into bitumen or adhesive; (2) the process of pressing granules coating during the manufacture of factory-pre-pared roofing; (3) the process ply sheet, aggregate, or other roofing components settle into hot- or applied bitumen via the force of gravity.
Emulsion: a dispersion of fine particles or globules in a liquid. (See Asphalt EmulsionBitumen 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 by extending the base sheet or one ply of felt beyond the edge of the field plies. After all overlying field plies or insulation are in place, theply is turned back onto the membrane and adhered. The envelope is to prevent bitumen seepage from the edge of the membrane.
EPDM: Ethylene Propylene Diene Monomer (See also Ethylene Propylene Diene.)
Equiviscous Temperature (EVT): the temperature at which a bitumen attains the viscosity for built-up membrane application.
Equiviscous Temperature (EVT) Application Range: the recommended bitumentemperature range. The range is approximately 25F (14C) above the EVT, thus giving a range of approximately 50F (28C). The EVT Range is measured in the mop cart or mechanical spreader just prior toof the bitumen to the substrate.
Equiviscous Temperature (EVT) for Asphalt: the recommended EVT for roofing (ASTM D312, Type I, II, III, or IV) is as follows:

– Mop Application: the temperature at which the asphalt’s apparent viscosity iscentipoise
– Mechanical Spreader Application: the temperature at which the asphalt’sviscosity is 75 centipoise
Note: If there are simultaneous mop and mechanical spreader applications, into avoid the use of two kettles, the EVT for mechanical spreader application may be used for both application techniques.

Ethylene Propylene Diene Terpolymer (EPDM) (Rubber Roof): designated nomenclature of ASTMa terpolymer of ethylene, propylene, and a diene. EPDM material is asynthetic elastomer.
Expansion Joint: a structural separation between two building elements that allowsmovement between the elements without damage to the roofing or waterproofing.
Exposed-Nail Method: a method of asphalt roll roofing application in which all nailsdriven into the adhered, overlapping course of roofing. Nails are exposed to the.
Exposure: (1) the traverse dimension of a roofing element or component notby an adjacent ele-ment or component in a roof covering. For example, theof any ply in a built-up roof membrane may be computed by dividing the feltminus 2 inches (51mm) by the number of shingled plies; thus, the exposure of 36(914mm) wide felt in a shingled, four-ply membrane should be approximately/2 inches (216mm)(See Figure 3) ; (2) the dimension of sidewall or roofing coveringis not covered or overlapped by the upslope course of component. The typicalfor a standard-size, 3-tab shingle is 5 inches (127mm), depending uponspecifications. 

Factory Seam: a splice/seam made by the manufacturer during the assembly ofof materials into large sheets.
Fascia: a vertical or steeply sloped roof or trim located at the perimeter of a building., it is a border for the low-slope roof system that waterproofs the interiorof the building.
Fasteners: any of a wide variety of mechanical securement devices and assemblies,nails, screws, cleats, clips, and bolts, which may be used to secure variousof a roof assembly.
Felt: a flexible sheet manufactured by the interlocking of fibers through a combinationmechanical work, moisture, and heat. Roofing felts may be manufactured principallywood pulp and vegetable fibers (organic felts), asbestos fibers (asbestos felts),fibers (fiberglass felts or ply sheet), or polyester fibers.
Ferrule: a small metal sleeve placed inside a gutter at the top. A spike is nailedthe gutter into the fas-cia board to hold the gutter in place. The ferrule acts asspacer in the gutter to maintain its original shape.
Fiberglass Insulation: blanket or rigid board insulation, composed of glass fiberstogether with a binder, faced or unfaced, used to insulate roofs and walls. Rigidusually have an asphalt and kraft paper facer.
Field of the Roof: the central or main portion of a roof, excluding the perimeter and.
Field Seam: a splice or seam made in the field (not factory) where overlapping sheetsjoined together using an adhesive, splicing tape, or heat- or solvent-welding.
Fire Resistance: the ability of a building component to act as a barrier to the spread ofand confine it to the area of origin.
Fishmouth: (also referred to as an Edge Wrinkle) (1) a half-cylindrical or half-conicalopening or void in a lapped edge or seam, usually caused by wrinkling orof ply sheets during installation; (2) in shingles, a half-conical opening formeda cut edge.
Flame Retardant: a substance which is added to a polymer formulation to reduce orits tendency to burn.
Flange: the projecting edge of a rigid or semi-rigid component, such as a metal edgeflange, skylight flange, flashing boot, structural member, etc.
Flash Point: the lowest temperature of a liquid at which it gives off vapors sufficient toan ignitable mix-ture with air near its surface.
Flashing: components used to weatherproof or seal the roof system edges at, penetrations, walls, expansion joints, valley, drains, and other placesthe roof covering is interrupted or terminated. For example, membrane basecovers the edge of the field membrane, and cap flashings or counterflash-ingsthe upper edges of the base flashing.
Flashing Cement: as used by the roofing industry, an ASTM D 2822 Type II roofthat is a trowelable mixture of solvent-based bitumen and mineral stabilizersmay include asbestos or other inorganic or organic fibers. Generally, flashingis characterized as vertical-grade, which indicates it is intended for use onsurfaces. (See Asphalt Roof Cement and Plastic Cement.)
Flashing Collar: (sometimes referred to as a Roof Jack or Flashing Boot) an accessory used to cover and/or seal soil pipe vents and other penetrations.

Galvalume: trade name for a coating, used over metal, that is composed of aluminumfor corrosion protection.
Galvanized Steel: steel coated with zinc for corrosion resistance.
Glass Felt: a sheet composed of bonded glass fibers, suitable for impregnation andin the manufac-ture of bituminous roofing and waterproofing materials, and. Glass Mat: a thin mat composed of glass fibers, woven or non-woven, with ora binder. This mat may serve as reinforcement for certain roof materials and.
Glaze Coat: (1) the top layer of asphalt on a smooth-surfaced built-up roof membrane;(2) a thin protective coating of bitumen applied to the lower plies or top ply of a built-roof membrane when application of addi-tional felts or the flood coat and aggregateare delayed.
Granule: (also referred to as Mineral or Ceramic Granule) opaque, natural, orcolored aggregate commonly used to surface cap sheets, shingles, andgranule-surfaced roof coverings.
Gravel Stop: a low profile upward-projecting metal edge flashing with a flange alongroof side, usually formed from sheet or extruded metal. Installed along theof a roof to provide a continuous finished edge for roofing material. Acts as astop during mop application of hot bitumen along a perimeter edge.

Headlap: the distance of overlap measured from the uppermost ply or course to thethat it laps over the undermost ply or course. 
Heat Welding: method of melting and fusing together the overlapping edges ofsheets or sections of polymer modified bitumen, thermoplastics or somethermoset roofing membranes by the application of heat (in the form of hot airopen flame) and pressure.
“Hot” or “Hot Stuff”: the roofer’s term for hot bitumen.
TM : a registered trademark of E.I. duPont de Nemours, Inc., for”chlorosulfonated polyethylene” (CSPE). (See Chlorosulfonated Polyethylene.)

Ice Dam: a mass of ice formed at the transition from a warm to a cold roof surface,formed by refreezing meltwater at the overhang of a steep roof, causing icewater to back up under roofing materials.
Infrared Thermography: a practice of roof system analysis where an infrared cameraused to measure the temperature differential of a roof surface to locate areas ofwet or moist insulation.
Insulation: any of a variety of materials designed to reduce the flow of heat, either frominto a building. (See also Thermal Insulation.)
Intake Ventilation: the fresh air that is drawn into a passive ventilation system throughtypically installed in the soffit or eave of a roof.
Interlayment: a felt, metal, or membrane sheet material used between courses ofslope roofing to improve the weather- and water-shedding characteristics of theroof covering during times of wind-driven rain and snow. Typically used withshakes.

Lap: that part of a roofing, waterproofing, or flashing component that overlaps orany portion of the same or another type of adjacent component.
Lap Cement: an asphalt-based roof cement formulated to adhere overlapping plies orroll roofing.
Lap Seam: occurs where overlapping materials are seamed, sealed, or otherwise.
Life Cycling Costing: a method of economic analysis that takes into account expectedover the useful life of an asset.
Loose-laid Membranes: membranes that are not attached to the substrate except atperimeter of the roof and at penetrations. Typically, loose-laid membranes are heldplace with ballast, such as water-worn stone, gravel, pavers, etc.

Mansard: a decorative steep-sloped roof on the perimeter of a building.
Mastic: see Asphalt Roof Cement.
Mat: a thin layer of woven, non-woven, or knitted fiber that serves as reinforcement tomaterial or membrane.
Material Safety Data Sheets (MSDS): a written description of the chemicals in a, and pertinent other data including such things as safe handling andprocedures. In accordance with OSHA regula-tions, it is the manufacturer’sto produce an MSDS and the employer’s responsibility to commu-nicatecontents to employees.
Mechanically-Fastened Membranes: generally used to describe membranes thatbeen attached at defined intervals to the substrate. Mechanical fastening may bewith various fasteners and/or other mechanical devices, such as plates or.
Membrane: a flexible or semi-flexible material, which functions as the waterproofingin a roofing or waterproofing assembly, and whose primary function is theof water.
Metal Film: a layer of foil made from a single metallic substance, or from an alloy, thatlaminated to a mem-brane during manufacture. The metal foil serves as thesurface of the membrane or flashing material.
Metal Flashing: accessory components fabricated from sheet metal and used toterminating roof covering edges. Frequently used as through-wall, cap flashing (coping), counterflashing, step-flashing, etc. (See Flashing.)
Mineral-Surfaced Roofing: roofing materials whose surface or top layer consists ofgranules.
Mineral-Surfaced Sheet: a roofing sheet that is coated on one or both sides withand surfaced with mineral granules.
Modified Bitumen: (1) a bitumen modified through the inclusion of one or more(e.g., atactic polypropylene, styrene butadiene styrene, etc.); (2) compositeconsisting of a polymer modified bitu-men often reinforced and sometimeswith various types of mats, films, foils, and mineral granules.
Moisture Relief Vent: a venting device installed through the roofing membrane tomoisture vapor pres-sure from within the roofing system.
Moisture Scan: the use of a mechanical device (capitance, infrared, or nuclear) tothe presence of moisture within a roof assembly. (See Non-Destructive Testing.)
Mole Run: a meandering buckle or ridging in a roof membrane not associated withor deck joints.
Mopping: the application of hot bitumen, with a roofer’s hand mop or mechanical, to the substrate or to the felts of a bituminous membrane.

Nailer: (commonly referred to as Blocking) a piece or pieces of dimensional lumber/or plywood secured to the structural deck or walls, which provide a receivingfor the fasteners used to attach membrane or flashing. Generally, it isthat nailers be the same thickness as the adjacent insulation, and maytreated with a non-oil-borne preservative, and be of sufficient width to fully supporthorizontal flashing flange of a metal flashing (where used).
Nailing: the application of nails. May be: (1) exposed nailing of roofing wherein nailare exposed to the weather; (2) concealed nailing of roofing wherein nail headsconcealed from the weather by an overlapping material.
Neoprene: a synthetic rubber (polychloroprene) used in liquid-applied andapplied elastomeric roof membranes or flashings.
Night Seal (or Night Tie-Off): a material and/or method used to temporarily seal aedge during construction to protect the roofing assembly in place frompenetration. Usually removed when roofing application is resumed.
Nineteen-Inch Selvage (Double-Coverage or Split-Sheet): a prepared roofing sheeta 17 inch (430mm) granule surfaced exposure and a non-granule surfaced 19(485mm) selvage edge. This material is some-times referred to as SIS,coverage, or according to ASTM Standard D 371-89, Standard SpecificationAsphalt Roll Roofing (Organic Felt) Surfaced with Mineral Granules, Wide Selvage.
Ninety-Pound: a prepared organic felt roll roofing with a granule surfacing that has aof approximately 90 pounds per 100 square feet, (4400 g/m).
NRCA: National Roofing Contractors Association

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

Parapet Wall: that part of a perimeter wall immediately adjacent to the roof whichabove the roof.
Partially-Attached: a roofing assembly in which the membrane has been “spot” to a substrate, usually with an adhesive or a mechanical device.
Penetration: (1) any object passing through the roof; (2) the consistency (hardness) ofbituminous material expressed as the distance, in tenths of a millimeter (0.1 mm),a standard needle penetrates vertically into a sample of material under specifiedof loading, time, and temperature.
Perlite: an aggregate used in lightweight insulating concrete and in preformed perliticboards, formed by heating and expanding siliceous volcanic glass.
Pipe Boot: prefabricated flashing piece used to flash around circular pipe.
Pitch-Pocket (Pitch-Pan): a flanged, open bottomed enclosure made of sheet metalother material, placed around a penetration through the roof, filled with grout andor polymeric sealants to seal the area around the penetration.
Plastic Cement: a roofing industry generic term used to describe Type I asphalt roofthat is a trowel-able mixture of solvent-based bitumen, mineral stabilizers,fibers and/or fillers. Generally, intended for use on relatively low slopes ‹ notsurfaces. (Also see Asphalt Roof Cement and Flashing Cement.)
Polymer: a natural or synthetic chemical compound of high molecular weight, or aof such com-pounds, formed when monomers (small individual molecules) areto form large long-chain molecules.
Polyvinyl Chloride (PVC): a synthetic thermoplastic polymer prepared from. PVC can be com-pounded into flexible and rigid forms through the useplasticizers, stabilizers, fillers, and other modifiers; rigid forms are used in pipes;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 in which consideration has been madedesign for all loading deflections of the deck, and additional roof slope hasprovided to ensure drainage of the roof area within 48 hours of rainfall, duringdrying conditions.
Primer: (1) a thin, liquid-applied solvent-based bitumen that may be applied to ato improve the adhe-sion of subsequent applications of bitumen; (2) a materialis sometimes used in the process of seaming single-ply membranes to preparesurfaces and increase the strength (in shear and peel) of the field splice.
Protected Membrane Roof (PMR): an insulated and ballasted roofing assembly, inthe insulation and ballast are applied on top of the membrane (sometimesto as an “inverted roof assembly”).
Puncture Resistance: extent to which a material is able to withstand the action of aobject without perforation. Purlin: horizontal secondary structural member thatloads from the primary structural framing.
PVC: Polyvinyl Chloride.

R-Value: the resistance to heat transfer of a material. Insulators have relatively high R.
Re-Cover: the addition of a new roof membrane or steep-slope roof covering over aportion of an exist-ing roof assembly. This process does not involve removal ofexisting roofing.
Reinforced Membrane: a roofing or waterproofing membrane that has beenby the addition or incorporation of one or more reinforcing materials,woven or nonwoven glass fibers, polyester mats or scrims, nylon, orsheeting.
Ridge Cap: a material or covering applied over the ridge of a roof.
Ridge Course: the last or top course of roofing materials, such as tile, roll roofing,, etc., that covers the ridge and overlaps the intersecting field roofing.
Ridge Vent: a ventilator located at the ridge that allows the escape of warm and/orair from the attic area or rafter cavity. Most ridge vents are eithermetal or flexible, shingle-over type.
Roll Roofing: smooth-surfaced or mineral-surfaced, coated, prepared felts.
Roof Assembly: an assembly of interacting roof components (includes the roof deck,retarder [if pre-sent], insulation, and roof covering).
Roof Curb: raised frame used to mount mechanical units (such as air conditioning orfans), skylights, etc.
Roof Seamer: machine that crimps neighboring metal roof panels together, or thatlaps of membrane sheets together using heat, solvent, or dielectric energy.
Roof Slope: the angle a roof surface makes with the horizontal, expressed as a ratio ofunits of vertical rise to the units of horizontal length (sometimes referred to as run).English units of measurement, when dimensions are given in inches, slope mayexpressed as a ratio of rise to run, such as 4:12, or as a percent.
Roof System: a system of interacting roof components, generally consisting ofor primary roof covering and insulation (not including the roof deck)to weatherproof and, sometimes, to improve the building’s thermal.

SBS: see Styrene Butadiene Styrene.
Seam: a joint formed by mating two separate sections of material. Seams may beor sealed in a variety of ways, including adhesive bonding, hot-air welding,welding, using adhesive tape, sealant, etc.
Seam Strength: the force or stress required to separate or rupture a seam in thematerial.
Self-Adhering Membrane: a membrane that can adhere to a substrate and to itself atwithout the use of an additional adhesive. The undersurface of aadhering membrane is protected by a release paper or film, which prevents thefrom bonding to itself during shipping and handling.
Self-Vulcanized Membrane: a membrane manufactured from compounds that areduring man-ufacture and installation, but whose polymers eventuallylink and cure during exposure.
Selvage: (1) an edge or edging that differs from the main part of a fabric,surfaced roll roofing or cap sheet, or other material; (2) a specially definedof the material (lined for demarcation), which is designed for some special, such as overlapping or seaming.
Selvage Edge: an edge designed for certain sheet good materials, e.g.,surfaced sheets. With mineral surfaced sheets, the surfacing is omitted over aof the longitudinal edge of the sheet (e.g., mineral sur-face cap sheet) in orderobtain better adhesion of the overlapping sheet.
Side Lap: the continuous longitudinal overlap of neighboring like materials. 
Single-Lock Standing Seam: a standing seam that utilizes one overlapping interlocktwo seam panels, in contrast with the double interlocking used in a doubleseam.
Single-Ply Membranes: roofing membranes that are field applied using just one layermembrane material (either homogeneous or composite) rather than multiple layers.
Single-Ply Roofing: a roofing system in which the principal roof covering is a singleflexible membrane, often of thermoset, thermoplastic, or polymer modifiedcompounds.
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

Slip Sheet: sheet material, such as reinforced kraft paper, rosin-sized paper, polyester, or polyethylene
, placed between two components of a roof assembly (such as betweenand insulation or deck) to ensure that no adhesion occurs between them,to prevent possible damage from chemical incompatibility, wearing, or abrasion ofmembrane.
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 theeave or in the soffit of a roof assembly.
Splice: bonding or joining of overlapping materials. (See Seam.)
Splice-Tape: cured or uncured synthetic rubber tape used for splicing membrane.
Spread Coating: a manufacturing process in which membranes are formed using a compound. After coating, the material passesa channel causing it to change from a paste to a solid membrane, in sheet.
Standing Seam: a metal roof system that consists of an overlapping or interlockingthat occurs at an upturned rib. The standing seam may be made by turning upedges of two adjacent metal panels and overlapping them, then folding orthem in a variety of ways.
Steep-Slope Roofing: a category of roofing that includes water shedding types of roofinstalled on slopes exceeding 3:12 or 25%.
Styrene Butadiene Rubber: high molecular weight polymers having rubber-like, formed by the random copolymerization of styrene and butadiene.
Styrene Butadiene Styrene Copolymer (SBS): high molecular weight polymers thatboth thermoset and thermoplastic properties, formed by the blockof styrene and butadiene monomers. These polymers are used asmodifying compound in SBS polymer modified asphalt roofing membranes torubber-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).

Tapered Edge Strip: a tapered insulation strip used to (1) elevate and slope the roofthe perimeter and at curbs, and (2) provide a gradual transition from one layer ofto another. Taping: (1) the technique of connecting joints between insulationor deck panels with tape; (2) the technique of using self-adhering tape-liketo seam or splice single-ply membranes.
Tar: a brown or black bituminous material, liquid or semi-solid in consistency, in whichpredominating con-stituents are bitumens obtained as condensates in theof coal, petroleum, oil-shale, wood, or other organic materials.
Termination: the treatment or method of anchoring and/or sealing the free edges ofmembrane in a roofing or waterproofing system.
Termination: the treatment or method of anchoring and/or sealing the free edges ofmembrane in a roof-ing or waterproofing system.
Thermal Barrier: a material applied over polyurethane foam designed to slow therise of the foam during a fire and delay its involvement in the fire. Thermalfor use with SPF must have a time rat-ing of not less than 15 minutes.
Thermal Block: a compression-resistant insulation block installed between thesteel and the panel to maintain insulation value.
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 theof thermal conductivity (k) or thermal conductance (C). The formula forresistance is: R = 1 or R = 1 or R = Thickness in inches C k k

UL Label: an identification label or seal affixed to a roofing product or package withauthorization of Underwriters Laboratories, Inc. The presence of the label indicatesthe product has met certain perfor-mance criteria.
Underlayment: an asphalt-saturated felt or other sheet material (may beadhering) installed between the roof deck and the roof system, usually used in aslope roof construction. Underlayment is primarily used to separate the rooffrom the roof deck, to shed water, and to provide secondary weathertection for the roof area of the building.
Underwriters Laboratories, Inc. (UL): an organization that tests, rates and classifiesassemblies for their resistance to: fire, impact, leakage, corrosion of metal, and wind uplift.
Uplift: see Wind Uplift.

Vapor Migration: the movement of water vapor from a region of high vapor pressure toregion of lower vapor pressure.
Vapor Pressure: the pressure at any given temperature exerted by a vapor that is inwith its liquid or solid form.
Vapor Retarder: material installed to impede or restrict the passage of water vapora roof assembly.Vapor Migration: the movement of water vapor from a regionhigh vapor pressure to a region of lower vapor pressure.
Vapor Pressure: the pressure at any given temperature exerted by a vapor that is inwith its liquid or solid form.
Vapor Retarder: material installed to impede or restrict the passage of water vapora roof assembly.
Vermiculite:  aggregate used in lightweight insulating concrete, formed by theand consequent expansion of a micaceous material.
Volatile Organic Compounds (VOC): organic materials which evaporate at normaland pressures; organic materials which have vapor pressures greater0.1mm Hg at one atmosphere.
Vulcanization: any of various processes by which natural or synthetic rubber or othermaterials may be cured or otherwise treated (i.e., exposed to chemicals,, or pressure) to render them non-thermo-plastic, and which improve their elasticphysical properties.

Weep Holes: small openings whose purpose is to permit drainage of water thatinside a building component (e.g., a brick wall, skylight frame, etc.).
Wicking: the process of moisture movement by capillary action, as contrasted toof water vapor.
Wind Load: force exerted by the wind on a structure or part of a structure.
Wind Uplift: the force caused by the deflection of wind at roof edges, roof peaks or, causing a drop in air pressure immediately above the roof surface. Thisis then transmitted to the roof surface. Uplift may also occur because of theof air pressure underneath the membrane and roof edges, where it canthe membrane to balloon and pull away from the deck.