Calibrate: (1) To correlate the readings of an instrument with those of a standard in order to check the instrument’s accuracy. (2) To adjust to take external factors into account or to allow comparison with other data.
Cap Flashing: (1) Usually composed of metal and functions to cover or shield the upper edges of the membrane base flashing wall flashing. (2) A flashing used to cover the top of various building components, such as parapets or columns. (See Flashing.)
Cap Sheet: A sheet, often granular-surfaced, used as the top ply of some built-up or modified bitumen roof membranes and/or flashings.
Capacitance: The ratio of the change in an electric charge in a system to the corresponding change in its electric potential. The unit of capacitance is the farad. Capacitance opposes changes in voltage.
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.
Capacitor: a device used to store an electric charge. A simple capacitor consists of two conductors separated by an insulator.
Capacitor Bank: A group of several capacitors of the same rating that are connected in series or parallel with each other to store electrical energy. The resulting bank is then used to counteract or correct a power factor lag or phase shift in an alternating current (AC) power supply.
Caulk: (1) 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. (2) To plug and make tight against leakage (as a boat or its seams, the cracks in a window frame, or the joints of a pipe).
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.

Cavity Wall: (1) An exterior wall usually of masonry, consisting of an outer and inner width separated by a continuous air space, but connected together by wire or sheet metal tiles. (2) A usually masonry wall built in two thicknesses separated by an air space that provides thermal insulation.
Centigrade (Celcius): Temperature scale of the metric system based on 0° as the freezing point of water and 100° as the boiling point of water.
Certification: (1) The action or process of providing someone or something with an official document attesting to a status or level of achievement. (2) An official document attesting to a status or level of achievement.
Certified: (1) To attest or confirm in a formal statement. (2) To officially recognize someone or something as possessing certain qualifications or meeting certain standards.
Certify: (1) To declare a thing true, accurate, certain, etc., by formal statement, often in writing verify. (2) To guarantee the quality or worth of. (3) To assure; make certain; or approve. (4) To issue a certificate or license to.
Circuit Breaker: An overcurrent device that operates on the principles of temperature rise or the strength of a magnetic field. Circuit breakers may use either principle or both at the same time.
Coal Tar: (1) A dark brown to black colored, semi-solid hydrocarbon produced by the distillation of coal. Coal tar pitch is further refined to conform to various roofing grade specifications. (2) Tar obtained by distillation of bituminous coal.
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”.
Coefficient of Thermal Expansion: The coefficient of change in dimension of a material per unit of dimension per degree change in temperature.
Composite Material: A combination of two or more materials differing in form or composition on macro scale. The constituents of the composite retain their identities; that is, they do not dissolve or merge completely into one another although they do act in concert. Normally the components of the composite can be physically identified and exhibit an interface between one another.
Conductance, Thermal (C): 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.
Conductor: A material whose atoms have free electrons, allowing current to pass though the material easily. Conductors are generally restricted to those materials that have atoms with less than one-half the number of electrons required to fill the outer shell of the atom.
Contact Radiometer: An infrared thermometer designed for contact temperature measurements. Contact radiometers are usually constructed with a mirrored cavity around their lens.
Core Sample: A small sample of the subject area (roof system, hull laminate, etc.) taken with a hole
saw or similar mechanical cutting device. Sample size can vary; the typical size is two (2) inch diameter. Critter: A living creature.
Critter Control Professional: A person who is licensed and/or certified to perform animal control and/or removal by the State(s) or region(s) in which they operate.
