"C" section—A member formed from steel sheet in the shape of a block "C", that may be used either singularly or back to back.

Calender—A machine with two or more rolls, operating at selected surface speeds and controlled temperatures, for sheeting, laminating, skim coating (topping) and a friction coating to a controlled thickness or surface characteristic, or both.

Calorie—The amount of heat required to raise 1 gram of water 1 degree Celsius.

Camber—A predetermined curvature designed into a structural member to offset the anticipated deflection when loads are applied.

Canopy—Any overhanging or projecting roof structure with the extreme end usually unsupported.

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.

Cantilevered beam—A projecting beam that is supported and restrained at one end only.

Cap flashing—See Flashing.

Cap sheet—A granule-surfaced coated felt used as the top ply of a built-up roofing membrane.

Capacitance—The ratio of the charge to the potential difference between two conducting elements separated by a nonconductor.

Capillary action—That action which causes movement of liquids by surface tension when in contact with two adjacent surfaces such as panel sidelaps.

Capital cost—the costs of acquiring, substantially improving, expanding, changing the functional use of, or replacing a building or building system.

Catalyst—A substance that causes or changes the rate of a chemical reaction.

Cationic emulsion—An emulsion in which the emulsifying system establishes a predominance of positive charges on the discontinuous phase.

Caulk—To seal and make weather-tight the joints, seams, or voids by filling with a waterproofing compound or material.

Caulking—A composition of vehicle and pigment, used at ambient temperatures for filling joints, that remains plastic for an extended time after application.

Cavity wall—A wall built of masonry units arranged to provide a continuous air space within the wall (with or without insulating material) and in which the inner and outer wythes of the wall are tied together with metal ties or headers.

Centistoke—Unit measurement of viscosity-i.e., resistance to flow.

Chain scission—Breaking of chemical bonds between carbon atoms by U. V. photo-oxidation, a reversal of the asphalt-blowing polymerization process that produces long chainlike hydrocarbon chains, resulting in embrittlement and cracking.

Chalk resistance—A measurement of performance for paint systems; the ability to resist a dusty/chalky appearance over time.

Chalking—A powdery residue on the surface of a material resulting from degradation or migration of an ingredient, or both.

Channel cold formed—A structural member produced from coiled steel stock on a series of rolls at normal room temperatures; limited to light gage material.

Channel—hot rolled—A member formed while in a semi-molten state at the steel mill to a general shape having standard dimensions and properties specified by AISC or the steel producer.

Channel mopping— See Strip mopping, under Mopping
Charging current—The transient current which flows to charge a capacitor.

Chlorinated polyethylene— (CPE)—Family of polymers produced by chemical reaction of chlorine on the linear backbone chain of polyethylene. The resultant rubbery thermoplastic elastomers presently contain 25-45% chlorine by weight and 0-25% crystallinity. CPE can be vulcanized but is usually used in a nonvulcanized form.

Chlorosulfonated polyethylene—(CSPE)—Family of polymers that are produced by polyethylene reacting with chlorine and sulfur dioxide. Present polymers contain 25-43% chlorine and 1.0-1.4% sulfur. They are used in both vulcanized and nonvulcanized forms. Most membranes based on CSPE are nonvulcanized. ASTM designation for this polymer is CSM. Best known by the DuPont Tradename "Hypalon".

Clip—A plate or angle used to fasten two or more members together.

Closure strip—A resilient strip such as neoprene, flat on one side and formed to the contour of ribbed sheets on the other, used to close openings created by joining metal sheets and flashings.

Coefficient of thermal expansion—The change in length per unit of length for a unit change in temperature. (Thus the coefficient per °F must be multiplied by 1.8 for the coefficient per °C.)

Coal tar—A dark brown to black cementitious material produced by the destructive distillation of coal.

Coal tar felt—A felt saturated with refined coal tar

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Coal tar pitch—A dark brown to black, solid cementitious material obtained as residue in the partial evaporation or distillation of coal tar.

Coalesce—To grow together into one body, as chemicals and vapors combine into one entity.

Coated fabric—Fabrics which have been impregnated and/or coated with a plastic 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 sheet (or felt)—(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 weight—Weight of coating on surface (both sides), usually expressed in ounces per sq. ft. or grams per sq. meter.
Coil coating—The application of an organic finish to a coil of metal using a continuous process.

Cold flow—Slow deformation, under gravitational force, at or below room temperature. (See Creep).

Cold forming—The process of using press brakes, roll formers, etc., to shape steel into desired cross sections at room temperature.

Cold process roofing—A continuous, semiflexible membrane consisting of plies of felts, mats, or fabrics laminated on a roof with alternate layers of roof cement and surfaced with a cold applied coating.

Cold working—Deforming metal plastically at a temperature lower than the recrystalization temperature.

Collateral load—All specified additional dead loads other than the metal building framing, such as sprinklers, mechanical and electrical systems, and ceilings.

Collector box—Transition piece between a gutter and downspout to facilitate water flow.

Color retention—The measurement of performance for paint systems testing the ability to resist fading.

Column—A primary member used in a vertical position on a building to transfer loads from main roof beams, trusses, or rafters to the foundation.

Compound—An intimate admixture of a polymer(s) with all the materials necessary for the finished product.

Compression — The decrease in length produced in a test specimen due to a composite load.

Compression set— The residual deformation of a material after removal of the compressive stress.

Compressi ve deformation — The decrease in length produced in the gage length of the test specimen by a compressive load. It is expressed in units of length. (ASTM D-1621)

Compressive strain — The ratio of compressive deformation to the gage length of the test specimen — that is, the change in length per unit of original length along the longitudinal axis. It is expressed as a dimensionless ratio.

Compressive strength — Procedure A — The stress at the yield point if a yield point occurs before 10% deformation. In the absence of such a yield point, it is the stress at 10% deformation.

Compressive strength — Procedure B — The same as in Procedure A, except substitute "2% strain" for "10% deformation". (ASTM D-1621)

Compressive stress — A diagram in which values of compressive stress are plotted as ordinates against corresponding values of compressive strain as abscissas. (ASTM D-1621)

Compressive stress (nominal) — The compressive load per unit area of minimum original cross section within the gage boundaries carried by the test specimen at any given moment. It is expressed in force per unit area. (ASTM D-1621)

Compressive yield point — The first point on the stress-strain diagram at which an increase in strain occurs without an increase in stress. (ASTM D-1621)

Condensation — The conversion of water vapor or other gas to liquid as the temperature drops or atmospheric pressure rises. (See also Dew point)

Condensation polymerization — Polymerization in which monomers are linked together with the splitting off of water or other simple molecules.

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.

Conductivity (electrical) — The reciprocal of electrical resistance.

Conductivity (thermal)— The time rate of transfer of heat by conduction through a unit thickness across unit area for unit difference of temperature.

Conductivity, thermal — The thermal transmission, by conduction only, in unit time through unit area between two isothermal surfaces of an infinite slab of a homogeneous material of unit thickness, in a direction perpendicular to the surface, when unit temperature difference is established between the surfaces. k=(W/m»K) k=(Btu/h«ft2«°F)

Continuity—The terminology given to a structural system denoting the transfer of loads and stresses from member to member, as if there were no connections.
Continuous beam—A beam spanning over three or more supports.

Contractor—See Builder.

Coping—A covering on top of a wall exposed to the weather, usually sloped to carry off water.

Copolymer—A mixed polymer, the product of polymerization of two or more substances at the same time.

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.

Counting interval—The time period during which meter detector tubes are measuring nuclear backscatter. Since isotopic discharges (disintegrations) occur randomly, a mean average can be obtained after a suitable interval. Precision improves by 30 percent when the time segment is doubled. Normal counting intervals range to 30 seconds.

Coverage—The surface area to be continuously covered by a specific quantity of a particular material.

Covering—The exterior roof and wall covering for a metal building system.

CPM—Counts per minute.

Cream Time—This is the time, measured in seconds at a given temperature, when the "A" and "B" components of a polyurethane foam compound will begin to expand after being mixed through the spray gun.

Creep—The dimensional change with time of a material under load, following the initial instantaneous elastic deformation. Creep at room temperature is sometimes called cold flow.

Creep modulus—The ratio of initial applied stress to creep strain.
Creep strain—The total strain, at any given time, produced by the applied stress during a creep test.
NOTE: The term creep, as used in this method, reflects current plastics engineering usage. Plastics have a wide spectrum of retardation times and the elastic portions of strain cannot be separated in practice from none las tic.

Cricket—A relatively small, elevated area of a roof constructed to divert water from a horizontal intersection of the roof with a chimney, wall, expansion joint or other projection.

Cross-Unking—A general term referring to the formation of chemical bonds between polymeric chains to yield an insoluble, three dimensional polymeric structure. Cross-linking of rubbers is vulcanization, qv.

CRT—Cathode ray tube—used as TV picture tubes, display on IR cameras, etc.

Curb—A raised member used to support roof penetrations such as skylights, hatches, etc.

Cure—To change the properties of a polymeric system into a more stable, usable condition by the use of heat, radiation, or reaction with chemical additives.
NOTE: Cure may be accomplished, for example, by removal of solvent or cross-linking.

Curie—The official unit of radioactivity, defined as 3.70 x 10'10 degrees disintegrations per second. (See Roentgen)

Curing—See Vulcanization.

Curled felt—BUR membrane defect characterized by a continuous, open longitudinal seal with top felt rolled back from underlying felt.

Curtain wall—Perimeter wall panels which carry their own weight and wind load.

Cutback—Solvent-thinned bitumen used in cold process roofing adhesives, flashing cements, and roof coatings.

Cutoff—A detail designed to prevent lateral water movement into the insulation where the membrane terminates at the end of a days work, or used to isolate sections of the roofing system. It is usually removed before the continuation of the work.