This glossary contains many useful terms and definitions that will help you understand much of the work we do at ROOFCORP.

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Calender: (1) to press between rollers or plates in order to smooth and glaze or to thin into sheets; (2) a machine for calendering.

Camber: a slight convexity, arching or curvature (as of a beam, roof deck or road).

Canopy: any overhanging or projecting roof structure, typically over entrances or doors.

Cant: in SPF-based roofing, a beveling of foam at horizontal/vertical joints to increase strength and promote water run off.

Cant strip: a beveled strip used under flashings to modify the angle at the point where the roofing or waterproofing membrane meets any vertical element.

Cap flashing: (1) usually composed of metal, used to cover or shield the upper edges of the membrane base flashing wall flashing; (2) a flashing used to cover the top of various buildings components, such as parapets or columns. (see Flashing and Coping.)

Cap sheet: a sheet, often granule-surfaced, used as the top ply of some built-up or modified bitumen roof membranes and/or flashings.

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

Capillary action: (1) the action by which the surface of a liquid where it is in contact with a solid is elevated or depressed depending on the relative attraction of the molecules of the liquid for each other and for those of the solid; (2) the siphoning of liquid into a joint or void between two adjacent surfaces.

Catalyst: an ingredient that initiates a chemical reaction or increases the rate of a chemical reaction when combined with another chemical.

Cathodic: A metal or material that readily attracts electrons from an anodic material in the presence of an electrolyte (see Galvanic Series).

Caulk: a composition of vehicle and pigment used at ambient temperatures for filling/sealing joints or junctures, that remains elastic for an extended period of time after application.

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

Cavitation: the formation of a partial vacuum or cavity in a liquid.

Cavity wall: an exterior wall usually of masonry, consisting of an outer and inner withe separated by a continuous air space, but connected together by wire or sheet-metal tiles.

C-channel: a structural framing member.

Cellular glass insulation: A rigid closed-cell insulation board made from crushed glass and hydrogen sulfide gas.

Cementitious waterproofing: heavy cement-based compounds and various additives that are mixed and packaged for use in a dry form; the packaged mixture is then mixed with water and liquid bonding agents to a workable concrete-like consistency.

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

Centistoke: a unit of viscosity; the ratio of a liquid's absolute viscosity to the density of that liquid. CERL: Construction Engineering Research Laboratory.

Chalk: a powdery residue on the surface of a material. Chalk line: a line made on the roof or other flat surface by snapping a taut string or cord dusted with colored chalk.

Chalking: the formation of a powdery surface condition from the disintegration of a binder or elastomer.

Channel flashing: in steep-slope roof construction, a type of flashing used at roof-to-wall junctures and other roof-to-vertical plane intersections where an internal gutter is needed to handle runoff. Commonly used with profile tile.

Chemical resistance: the ability to withstand contact with specified chemicals without a significant change in properties.

Chimney: stone, masonry, prefabricated metal or wood-framed structure, containing one or more flues, projecting through and above the roof.

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

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

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

Cleat: a continuous metal strip, or angled piece, used to secure metal components (also see Clip).

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: A non-continuous metal component or angle piece used to secure two or more metal components together. (see Cleat.)

Clipped gable: a gable cutback near the peak in a hip-roof form.

Closed-cut valley: a method of valley application in which shingles from one side of the valley extend across the valley while shingles from the other side are trimmed back approximately 2 inches (51 mm) from the valley centerline.

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

Coal tar: a dark brown to black colored, semi-solid hydrocarbon produced by the distillation of coal. Coal tar pitch is further refined to conform to the following roofing grade specifications:

Coal tar pitch: a coal tar used as the waterproofing agent in dead-level or low-slope built-up roof membranes and membrane waterproofing systems, conforming to ASTM Specification D 450, Type I.

Coal tar waterproofing pitch: a coal tar used as the dampproofing or waterproofing agent in below-grade structures, conforming to ASTM Specification D 450, Type II.

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 and membrane waterproofing systems, conforming to ASTM D 450, Type III.

Coal tar felt: a felt that has been saturated or impregnated 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, Asbestos Container."

Coarse orange peel surface texture: a surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is acceptable for receiving a protective coating because of the roundness of the nodules and valleys.

Coated base sheet: a coated felt intended to be used as a base ply in a built-up or modified bitumen roof membrane.

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 materials resulting from the application of a preformed film to a fabric by means of calendering.

Coated felt (Sheet): (1) an asphalt felt that has been coated on both sides with harder, more viscous asphalt; (2) a glass fiber felt that has been simultaneously impregnated and coated with asphalt on both sides.

Coating: a layer of liquid material applied to a surface for protection or appearance. Cobwebbing: a phenomenon observed during spray application characterized by the formation of web-like threads along with the usual droplets leaving the spray gun nozzle.

Code: a collection of laws (regulations, ordinances or statutory requirements) adopted by governmental authority. (see Building code and Model code.)

Coefficient of thermal expansion: the coefficient of change in dimension of a material per unit of dimension per degree change in temperature.

Cohesion: the molecular forces of attraction by which the body of a material is held together. Coil coating: the application of a finish to a coil of metal using a continuous mechanical coating process.

Cold forming: the process of shaping metal into desired profiles without the application of heat.

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

Cold roof assembly: a roof assembly configured with the insulation below the deck, not typically in contact with the deck, allowing for a ventilation space. The temperature of the roof assembly remains close to the outside air temperature.

Color stability: the ability of a material to retain its original color after exposure to weather.

Column: in structures, a relatively long, slender structural compression member such as a post, pillar or strut; usually vertical which acts in (or near) the direction of its longitudinal axis.

Combing ridge: a term used to describe an installation of finishing slate or wood at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge. Combustible: capable of burning.

Combustion: a chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow or flames; the process of burning.

Compatible materials: two or more substances that can be mixed, blended, or attached without separating, reacting, or affecting the materials adversely.

Composition shingle: a unit of asphalt shingle roofing.

Composite board roof insulation: rigid board insulation generally comprised of perlite or wood fiberboard factory bonded to polyisocyanurate or polystyrene.

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.

Compressive strength: the property of a material that relates to its ability to resist compression loads.

Concealed-nail method: a method roofing application in which all nails are driven into the underlying course of roofing and covered by a subsequent, overlapping course.

Concealed plate: see Cover plate. Condense: to make denser or more compact, as when a material (e.g., water vapor) changes from its gas phase to its liquid phase.

Condensate: the liquid resulting from the condensation of a gas.

Condensation: the conversion of water vapor or other gas to liquid phase as the temperature drops; the act or process of condensing.

Conditioning: the storage of a material specimen under specified temperature, humidity, etc. for a specified time prior to testing.

Conductance, Thermal: the thermal transmission in unit time through unit area of a particular body or assembly having defined surfaces, when unit average temperature difference is established between the surfaces. C=Btu/h·ft2·°F (C=W/m2·K).

Conductor head: an enlargement or catch basin at the top of a downspout or leader to receive rainwater from a gutter or scupper. Construction joint: (1) a joint where two successive placements of concrete meet; (2) a separation provided in a building which allows its component parts to move with respect to each other.

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

Contamination: the process of making a material or surface unclean or unsuited for its intended purpose, usually by the addition or attachment of undesirable foreign substances.

Control joint: a groove which is formed, sawed, or tooled in a concrete or masonry structure to regulate the location and amount of cracking and separation resulting from the dimensional change of different parts of the structure, thereby avoiding the development of high stresses.

Coping: the covering piece on top of a wall exposed to the weather, usually made of metal, masonry, or stone and sloped to carry off water.

Copolymer: the product of polymerization of two or more substances (as two different isomers) together. Copolymerization: a chemical reaction that results in the bonding of two or more dissimilar monomers to produce large, long-chain molecules that are copolymers.

Copper: a natural weathering metal used in metal roofing or flashing; typically used in 16 ounce per square foot (0.56 mm) and 20 ounce per square foot (0.69 mm) thicknesses.

Core cut or core sample: (1) a sample from a low-slope roof system taken for the purpose of obtaining primarily qualitative information about its construction. Typically, core cut analysis can verify or reveal the type of membrane surfacing; the type of membrane; the approximate number of plies; the type, thickness and condition of the insulation (if any); and the type of deck used as a substrate for the roof system. (2) for in SPF-based roof systems, core cuts are used to obtain both quantitative and qualitative information, such as the thickness of the foam, the thick-ness and adhesion of the coating, thickness of individual passes and adhesion between passes and the adhesion of the foam to its substrate.

Cornice: the decorative horizontal molding or projected roof overhang.

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 or elastomeric sheeting secured on or into a wall, curb, pipe, rooftop unit or other surface, to cover and protect the upper edge of a base flashing and its associated fasteners. Course: (1) the term used for a row of roofing material that forms the roofing, waterproofing or flashing system; (2) one layer of a series of materials applied to a surface (e.g., a five-course wall flashing is composed of three applications of roof cement with one ply of felt or fabric sandwiched between two layers of roof cement).

Cover board: an insulation board used over closed cell plastic foam insulation (e.g., polyisocyanurate) to prevent blistering when used in conjunction with hot bituminous membranes. Suitable cover board insulation are glass-faced siliconized gypsum board, glass-fiber board, perlite board, wood-fiber board or mineral-fiber board. Cover boards are also recommended between polyisocyanurate insulation and single ply membranes to protect the polyisocyanurate.

Cover plate: a metal strip sometimes installed over or under the joint between formed metal pieces.

Coverage: the surface area uniformly covered by a specific quantity of a particular material at a specific thickness. CPA: copolymer alloy.

Crack: a nonlinear separation or fracture occurring in a material. Cream time: time in seconds (at a given temperature) when the A and B components of polyurethane foam will begin to expand after being mixed. Recognizable as a change in color of the materials.

Cricket: a relatively small area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection. (see Saddle.) Cross-linking: the formation of chemical bonds between polymeric chains. Cross-linking of rubber is referred to as vulcanization or "curing."

CRREL: Cold Regions Research and Engineering Laboratory. Crystalline waterproofing: a compound of cement, quartz or silica sand, and other active chemicals that are mixed and packaged for use in a dry powder form; the packaged mixture is then mixed with water and applied to a concrete surface where it penetrates into the pores of concrete.

CSPE: chlorosulfonated polyethylene.

Cupola: a relatively small roofed structure, generally set on the ridge or peak of a main roof area for ventilation or aesthetic purposes.

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.

Cure time: the time required for a material to reach its desirable long-term physical characteristics.

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

Curing agent: an additive in a coating or adhesive that results in increased chemical activity between the components with an increase or decrease in rate of cure.

Curing compound: a liquid that is sprayed or otherwise applied to newly placed concrete which retards the loss of water during curing.

Cutback: solvent-thinned bitumen used in cold-process roofing adhesives, roof cements and roof coatings.

Cutoff: a permanent detail designed to prevent lateral water movement in an insulation system and used to isolate sections of a roofing system. (Note: A cutoff is different from a tie-in, which may be a temporary or permanent seal.) (see Tie-In.)

Cutout: the open portions of a strip shingle between the tabs. Sometimes referred to as a keyway.