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Glossary
BUTT JOINT A joint or seam formed by joining separate
sections of membrane at the edges without overlap (i.e., edge
to edge). Once the edges have been joined, the seam is
usually covered and sealed with a narrow strip of membrane
material or compatible tape.
BUTYL A rubber material produced by copolymerizing
isobutylene with a small amount of isoprene. Butyl is variously
manufactured into sheet goods, blended with other rubber
materials, and is often used to make sealants and adhesives.
CALENDERING A manufacturing process by which polymeric
membranes and sheeting are produced. The finished material
is formed by passing it between the nips of a series of large
counter-rotating steel rollers which produces a film or sheet of
uniform thickness. The device used for this purpose is a
calender.
CAMBER A slight convex curve of a surface, such as in a
pre-stressed concrete deck.
CANT STRIP A beveled strip used under flashings of
bituminous systems to modify the angle at the point where the
roofing or waterproofing membrane meets any vertical
element.
CAP FLASHING See COUNTERFLASHING.
CAP SHEET A granule surfaced, coated felt used as the top
ply of a roofing membrane.
CELLULAR GLASS INSULATION A rigid roof insulation
board composed of heat-fused, closed glass cells blown with
hydrogen sulfide.
CHANNEL MOPPING See MOPPING.
CHLORINATED POLYETHYLENE (CPE) A thermoplastic
material, used for single ply membranes, which is composed of
high molecular weight polyethylene which has been
chlorinated–a process which yields a flexible rubber-like
material.
CHLOROSULFONATED POLYETHYLENE (CSPE) A
synthetic, rubber-like thermoset material, based on high
molecular weight polyethylene with pendant sulphonyl chloride
groups, usually formulated to produce a self-vulcanizing
membrane.
COAL TAR FELT A felt that has been saturated with refined
coal tar.
COAL TAR PITCH A dark brown to black, solid material
obtained as a residue in the partial evaporation or distillation of
coal tar.
COATED 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.
COEFFICIENT OF THERMAL EXPANSION The change in
dimension of a material as a function of temperature. It is
usually reported in inches per inch per °F or millimeters per
millimeter per °C.
COLD PROCESS ROOFING A continuous, semi-flexible
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.
COMPOSITE BOARD A roof insulation board composed of
two different types of insulating materials bonded together to
form one integral product.
COMPRESSIVE STRENGTH The ability of roofing materials
and components to resist deformation or other damage
caused by the weight or compression of either "live" or "dead
loads." High compressive strength may be especially important
in insulation boards.
CONDENSATION The conversion of water vapor or other gas
to liquid as the temperature drops or atmospheric pressure
rises.
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/hr·ft2·°F) [C=W/m2K]
CONTACT CEMENTS Adhesives which may be used to
adhere or bond together various roofing components. The
adhesive is applied to the surfaces to be joined in a liquid
state, and then allowed to dry before the surfaces are mated.
The bond is formed immediately as the surfaces touch.
CONTROL JOINT A raised, flashed assembly (typically a
single- or double-wood member attached to a wood base
plate) that is anchored to the roof deck. It is used to relieve
thermal stresses in a roof system where an expansion joint is
not required, or to separate large roof areas (sometimes
between expansion joints), and may be used to facilitate
installation of tapered insulation.
COPING A covering on top of a wall exposed to the weather,
usually sloped to carry off water.
CORE A small sample removed from a roof assembly, usually
in conjunction with moisture surveys or investigations.
COUNTERFLASHING Formed metal, elastomeric sheeting or
other material 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.
COVERAGE The surface area to be continuously covered by a
specific quantity of a particular material.
