Blister. A spongy, humped portion of a roof membrane, formed by
entrapped air/vapor mixture under pressure, with the blister
chamber located either between felt plies (i.e., interply) or at
the membrane-substrate interface (interfacial).
Blocking. Continuous wood components anchored to the deck at
roof perimeters and openings and doubling as cross-sectional
fillers and anchorage bases, used in conjunction with nailers.
Brooming. The field procedure of pressing felts into a layer of
fluid, hot bitumen to obtain continuous adhesion - i.e.,
elimination of blister originating voids - of the bitumen film.
Btu (British thermal unit). Heat energy required to raise the
temperature of 1 pound of water 1F.
Built-up roof membrane. A continuous, semiflexible roof covering
of laminations or plies of saturated or coated felts or mats
alternated with layers of bitumen, usually surfaced with mineral
aggregate or asphaltic materials.
Roofer's term for plastic cement.
BUR. Abbreviation for built-up roof.
Camber. Upward deflection built into a structural member
subjected to flexural stresses to counteract the downward
deflection from gravity loads.
Cant strip. Strip of wood, wood-fiber, or perlite board,
triangular or trapezoidal in cross section, serving as
transitional plane between horizontal and vertical surfaces. The
cant provides backing for the stiff flashing felts of built-up
roof construction, reducing the risk of cracking by halving the
bend angle from 90 to 45 degrees.
Cap sheet. A mineral-surfaced, coated felt or mat used as the
top ply of a built-up roof membrane.
Centistoke (cs). Unit of viscosity (antonym of fluidity). Water
has a viscosity of roughly 1 cs; light cooking oil, l00 cs.
See Strip mopping, under Mopping.