Term Description

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


The formation of a partial vacuum or cavity in a liquid.

Cellular concrete

A poured-in-place roof deck material composed of Portland cement, water, a foaming agent or pregenerated foam and air. Its oven-dry density is about 24 to 32 pounds per cubic foot.

Cellular glass insulation

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

Cementitious board

Cement-based board stock with moisture-resistant, noncombustible core with cement as the primary binder that is used as a substrate board in a waterproofing or vegetative roof system.

Cementitious-wood fiber deck

Treated wood fibers bonded together with Portland cement or other resinous- or cementitious-type binder that are compressed and molded to form a structural material. Examples of product trade names are Tectum and Insul-rock.

Centimeter (cm)

A metric unit of measurement equal to one-hundredth (0.01) of a meter, or 0.393 inches.

Centipoise (cP or cPs)

A unit of measure of dynamic viscosity in the centimeter-gram-second system of units equal to one one-hundredth of a poise (1 P = 100 cP = 1 g•cm-1•s-1). (The viscosity of water at 70 F is 1 centipoise. The lower the number, the less viscous the material.)

Centistokes (cSt)

A unit of kinematic viscosity in the centimeter-gram-second system of units equal to one one-hundredth of a stokes (1 St = 100 cSt = 1 cm2•s-1); the ratio of a liquid's dynamic viscosity to its density.


A powdery residue on the surface of a material.


The formation of a friable powder on the surface caused by the disintegration of the binding medium by weather factors.

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.


In coatings, slight breaks in the film that do not penetrate to the previously applied coating or substrate; also termed "weather checking."

Chemical resistance

The ability to withstand contact with specified chemicals without a significant change in properties.


Stone, masonry, prefabricated metal or wood-framed structure containing one or more flues projecting through and above a roof.

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. Membranes in vulcanized and nonvulcanized forms are used; classified by ASTM D5019.


(1) A principal member of a truss, which extends from one end to the other, primarily to resist bending; (2) the straight line between two points on a curve; (3) the span of an arch.


A material used as the exterior wall enclosure of a building.


A continuous metal strip, or angled piece, used to secure metal components.


(1) An upward extension of enclosed space created by carrying a setback vertical wall (typically glazed) up and through the roof slope; (2) two intersecting shed roofs on different planes.


A non-continuous metal component or angle piece used to secure a metal panel to a substrate or two or more metal components together.

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 from the valley centerline.

Coal tar

A dark brown to black cementitious material produced by the destructive 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 D450, Type I. coal-tar waterproofing pitch: A coal tar used as the dampproofing or waterproofing agent in below-grade structures, conforming to ASTM D450, Type II.

coal-tar roof cement: A trowelable mixture of processed coal-tar base, solvents, mineral fillers and/or fibers; classified by ASTM D5643, "Coal Tar Roof Cement, Asbestos Free."

Coarse orange-peel surface texture

In spray polyurethane foam roofing, 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 polymer-modified bitumen roof membrane.