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This glossary was designed to help those not directly involved in roofing with their understanding of roofing terminology. Many technical and chemical terms were not included.

CABO: Council of American Building Officials

Calender: A machine used to laminate sheeting or for applying coating with a specified thickness and/or surface attribute.

Calendering: A specific process used to manufacture some membranes such as PVC.

Camber: A slight convex curve of a surface.

Canopy: An overhang, usually over entrances or driveways.

Cant: (1) Short for Cant Strip; (2) The act of installing foam at a right angle adjunct.

Cant Strip: A triangular-shaped strip of material used to ease the transition from a horizontal plane to a vertical plane. Cant strips can be made of wood, wood fiber, perlite, or other materials.

Cap Flashing: A material used to cover the top edge of base flashings or other flashings. (See also Coping.)

Cap Sheet: A granule-surfaced membrane often used as the top ply of BUR or modified roof systems.

Capacitance Meter: A device for locating moisture within a roof system by measuring the ratio of the change to the potential difference between two conducting elements that are separated by a non-conductor.

Catalyst: A substance that effects a chemical reaction and/or the rate at which a chemical reaction takes place. In roofing, catalysts are used in SPF roofing.

Cathodic: metals low in the Galvanic Series.

Caulk: A material with no elastomeric properties used for sealing joints.

Caulking: The act of sealing a joint or of material.

Cavitation: The vaporization of a liquid under the suction force of a pump which can create voids within the pump supply line. Cavitation will result in off-ratio foam in Sprayed Polyurethane Foam applications.

CCF: 100 cubic feet.

C-Channel: A structural framing member that, when viewed cross-sectionally, has the shape of a "C".

Cellulose: A complex carbohydrate, (C6H10O5)n, that is composed of glucose units, forms the main constituent of the cell wall in most plants, and is used in the manufacturing of organic roofing materials.

CERL: Construction Engineering Research Laboratory

CG&E: See Chopped Glass and Emulsion.

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

Chalk Line: (1) A string on a reel in a container that can hold chalk; (2) A line made on by pulling taut a string coated with chalk and snapping it.

Channel Flashing: Flashing with a built-in channel for runoff; used where roof planes intersect other vertical planes.

Chemical Resistance: A materials ability to retain its properties when it comes into contact with certain chemicals.

Chlorinated Polyethylene1 (CPE): CPE is a flexible material with high tear strength, good chemical resistance and patency towards UV radiation. As a result of the high chlorine content (typically 30%) it is inherently difficult to ignite, but releases hydrogen chloride during combustion. It suffers from an extremely high permeability to gas. Resistance to most inorganic chemicals is generally good, while resistance to hydrocarbons increases with increasing chorine content. The material is used mainly as an impact modifier for PVC and, to a lesser extent, LDPE and HDPE film.

Chlorosulfonated Polyethylene (NRCA Definition): A synthetic, rubber-like thermoset material, based on high molecular weight polyethylene with suphonyl chloride, usually formulated to produce a self-vulcanizing membrane. Chlorosulfonated Polyethylene or CSPE. Best know as Hypalon™, it was developed in 1951 by DuPont.

Chopped Glass and Emulsion (CG&E): A roof coating that consists of asphalt or clay emulsion and glass fiber reinforcement. The glass fiber comes in rope form and is mechanically chopped into small pieces and then mixed with the emulsion at the end of the spray gun so that the mixture is complete by the time the surfacing hits the top of the roof. Standard mixture is 9 gallons of emulsion and 3 pounds of glass fiber for every 100 square feet (36.5 Liters of emulsion and 1.5 kg of chopped glass for every 10 square meters). The CG&E coating is then usually surfaced with a fibered aluminum roof coating at rate of 1.5 gallons per 100 square feet (6 Liters per 10 square meters).

Cladding: A material used to cover the exterior wall of a building.

Cleat: A continuous metal strip used to secure two or more metal roof components together. Commonly used along with coping or gravel stop on tall buildings.

Clerestory (Clearstory): A room that extends above an abutting roof section of a building.

Clip: A small cleat. See 'Cleat' above.

Clipped Gable: A gable cut back at the ridge in a small hip configuration.

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 installed over the top of those and then trimmed back approximately 2 inches from the valley centerline.

Closure Strip: A material used to close openings created by joining metal panels or sheets and flashings.

Coal Tar Bitumen: A proprietary trade name for Type III coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.

Coal Tar Pitch: A type of coal tar used in dead-level or low-slope built-up roofs. It is not for use in roofs exceeding ¼" in 12" (2%) slope.

Coal Tar Felt: A roofing membrane saturated with refined coal tar.

Coal Tar Roof Cement: A trowelable mixture of processed coal tar base, solvents, mineral fillers and/or fibers.

Coarse Orange Peel Surface Texture: A surface showing a texture where nodules and valleys are approximately the same size and shape. This surface is generally acceptable for installing a protective coating.

Coated Base Sheet: An asphalt-saturated base sheet membrane later coated with harder, more viscous asphalt, thereby increasing its impermeability to moisture.

Coated Felt: An asphalt-saturated ply sheet that has also been coated on both sides with harder, more viscous asphalt.

Coating: A layer of material that is spray, roller, or brush applied over a surface for protection or sometimes decoration.

Cohesion: Mutual attraction by which the elements or particles of a body or substance are held together.

Coil Coating: The application of a finish to a coil of metal or other material.

Cold Forming: The process of shaping metal into desired configurations at ambient room temperature.

Cold Process Built-Up Roof: A roof consisting of multiple plies of roof felts laminated together with adhesives that usually come right out of a can or barrel and require no heating.

Collector Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Conductor Head.

Column: A vertical structural member placed on a footing or foundation used to support horizontal above-ground building components.

Combing Ridge: A term used to describe an installation of finishing slate at the ridge of a roof whereby the slates on one side project beyond to the apex of the ridge.

Combustible: Capable of igniting and burning.

Composition Shingle: A type of shingle used in steep-slope roofing and generally comprised of weathering-grade asphalt, a fiber glass reinforcing mat, an adhesive strip, and mineral granules.

Compounded Thermoplastics1 (NRCA Definition): 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.

Concealed-Nail Method: A method of installing asphalt roll roofing material in which all nails or fasteners are driven into the underlying roofing and covered by an overlapping course.

Condensate: The liquid resulting from condensation.

Condensation: The conversion of water vapor to liquid state when warm air comes in contact with a cold surface. (See also Dew Point.)

Conduction: The transmission or conveying of something through a medium or passage, especially the transmission of electric charge or heat through a conducting medium without perceptible motion of the medium itself.

Conductor Head: A component used to direct water from a through-wall scupper to a downspout. Also known as a Collector Head.

Construction Joint: A constructed joint where two successive installments of concrete come together.

Contact Cements: Adhesives used to adhere or bond roofing components.

Coping: the piece of material used to cover the top of a wall and protect it from the elements. It can be constructed from metal, masonry, or stone.

Copper: A reddish-brown element that conducts heat and electricity very well. It is also used as a primary roof material as well as a flashing component. Copper turns a greenish color after being exposed to the weather for a length of time and appears in the middle of the Galvanic Series.

Cornice: A horizontal projecting part that crowns the wall of a building.

Counter Batten: Wood strips installed vertically on sloped roofs over which horizontal battens are secured.

Counterflashing: Formed metal sheeting secured to walls, curbs, or other surfaces, for use in protecting the top edge of base flashings from exposure to weather.

Course: (1) The term used for each row of roofing material that forms the roofing or flashing system; (2) One of multiple layers materials applied to a surface. For example, a three-course flashing consists of a layer of mesh or other reinforcing material sandwiched between two layers roofing cement.

Cove: In roofing, a heavy bead of sealant material installed at the point where vertical and horizontal planes meet. It is used to eliminate the 90° angle. See also Fillet.

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

Coverage: The surface area covered by a material.

CPA: Copolymer Alloy.

CPE: Chlorinated Polyethylene.

Crack: A separation or fracture occurring in a material. See also Split.

Cream Time: Time in seconds at a given temperature when the A and B (isocyanate and resin) components of SPF will begin to expand after being mixed.

Creep: Movement of roof membrane causing the roof system to be deformed

Cricket: A roof component used to divert water away from curbs, platforms, chimneys, walls, or other roof penetrations and projections. See also Saddle.

Cross Ventilation: The effect of air moving through a roof cavity between vents.

CRREL: Cold Regions Research and Engineering Laboratory

Crow's Nest: See Cupola.

CSI: Construction Specifications Institute

CSM: ASTM designation for Chlorosulfonated polyethylene. (See CSPE.)

CSPE: Chlorosulfonated polyethylene.

Cupola: A relatively small roofed structure set on the ridge of a main roof area. Also known as a Crow’s Nest.

Curb: (1) A raised member used to support skylights, HVAC units, exhaust fans, hatches or other pieces of mechanical equipment above the level of the roof surface, should be a minimum of eight inches (8") in height; (2) A raised roof perimeter that is relatively low in height.

Cure: A process by which a material is forms permanent molecular linkages by exposure to chemicals, heat, pressure, and/or weathering.

Cure Time: The time necessary to effect curing.

Curing Agent: A material additive that alters chemical activity between the components resulting in a change in the rate of cure.

Curing Compound: A liquid that is applied to newly installed concrete which slows water loss while curing.

Cutback: Bitumen thinned by solvents that is used in cold-process roofing adhesives, roof cements, and roof coatings.

Cut-off: A detail designed to seal and prevent lateral water movement in an insulation system, and used to separate different sections of a roofing system.

Cutout: The open area between shingle tabs. Also known as a "throat".


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