Glossary of Commercial Roofing Terms
Click on a letter, to view the terms below.
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Aggregate: (1) crushed stone, crushed slag or water-worn gravel used for surfacing a built-up roof. (2) any granular mineral material.
Alligatoring: the cracking of the surfacing bitumen on a built-up roof, producing a pattern of cracks similar to an alligator's hide; the cracks may or may not extend through the surfacing bitumen.
Ambient Temperature: temperature of air - - air temperature.
Application Rate: the quantity (mass, volume or thickness) of material applied per unit area.
Area Divider: a raised, double wood member attached to a properly flashed wood base plate that is anchored to the roof deck. It is used to relieve thermal stresses in a roof system where no expansion joints have been provided.
Asbestos: (a group of natural, fibrous, impure silicate materials.
Asphalt: Asphalt: A dark brown to black material in which the predominating constituents are bitumen's, which occur in nature or are obtained in petroleum processing.
Asphalt, Air Blown: an asphalt produced by blowing steam through molten asphalt to modify its properties, normally used for highway bitumen.
Atactic Polypropylene: a group of high molecular weight polymers formed by the polymerization of propylene.
Back Nailing: the practice of blind nailing (in addition to hot mopping) all the plies of a substrate to prevent slippage. see Blind Nailing.
Ballast : an anchoring material, such as aggregate, precast pavers, which employ the force of gravity to hold (or assist in holding) membranes in place.
Base Flashing: see Flashing.
Base Ply: the base ply is the first ply when it is a separate ply and not part of a shingled system.
Base Sheet: a saturated or coated felt placed as the first ply in some multi-ply built up roof membranes.
Bentonite: a clay formed from decomposed volcanic ash, with a high content of the mineral montmorillonite; has the capacity of absorbing a considerable amount of water, and swells accordingly.
Bitumen: the generic term for an amorphous, semi-solid mixture of complex hydrocarbons derived from any organic source. Asphalt and coal tar are the two used in the roofing industry.
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