Accelerated Weathering: the process in which materials are exposed to a controlled environment where various exposures such as heat, water, condensation, or light are altered to magnify their effects, thereby accelerating the weathering process. The material’s physical properties are measured after this process and compared to the original properties of the unexposed material, or to the properties of the material that has been exposed to natural weathering.

 

Acrylic Coating: a coating system based on an acrylic resin. Generally, a latex-based coating system which cures by air drying.

 

Adhere: to cause two surfaces to be held together by adhesion, typically with asphalt or roofing cements in built-up roofing and with contact cements in some single-ply membranes.

 

Aggregate: rock, stone, crushed stone, crushed slag, water-worn gravel or marble chips used for surfacing and/or ballasting a roof system.

 

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.

 

Aluminum: a non-rusting metal sometimes used for metal roofing and flashing.

 

Ambient Temperature: the temperature of the air; air temperature.

 

APP: see Atactic Polypropylene.

 

Apron Flashing: a term used for a flashing located at the juncture of the top of the sloped roof and a vertical wall or steeper-sloped roof.

 

Architectural Panel: a metal roof panel, typically a double standing seam or batten seam; usually requires solid decking underneath and relies on slope to shed water.

 

Architectural Shingle: shingle that provides a dimensional appearance.

 

Area Divider: 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.

 

Asbestos: a group of natural, fibrous, impure silicate materials used to reinforce some roofing products.

 

Asphalt: a dark brown or black substance found in a natural state or, more commonly, left as a residue after evaporating or otherwise processing crude oil or petroleum. Asphalt may be further refined to conform to various roofing grade specifications:

Dead-Level Asphalt: a roofing asphalt conforming to the requirements of ASTM Specification D 312,Type I.

Flat Asphalt: a roofing asphalt conforming to the requirements of ASTM Specification D 312, Type II.

Steep Asphalt: a roofing asphalt conforming to the requirements of ASTM Specification D 312, Type III.

Special Steep Asphalt: a roofing asphalt conforming to the requirements of ASTM Specification D 312,Type IV.

 

Asphalt Emulsion: a mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.  These components are combined by using a chemical or a clay emulsifying agent and mixing or blending machinery.

 

Asphalt Felt: an asphalt-saturated and/or an asphalt-coated felt. (See Felt.)

 

Asphalt Primer: see Primer.

 

Asphalt Roof Cement: a trowelable mixture of solvent-based bitumen, mineral stabilizers, other fibers and/or fillers.

Asphalt Roof Cement, Asbestos-Free, Types I and II.

Type I is generally referred to as “plastic cement,” and is made from asphalt characterized as self-sealing, adhesive and ductile. (See Plastic Cement and Flashing Cement.) Type II is generally referred to as “vertical-grade flashing cement,” and is made from asphalt characterized by a high softening point and relatively low ductility. (See Plastic Cement and Flashing Cement.)

 

ASTM: American Society for Testing and Materials

 

Atactic Polypropylene: a group of high molecular weight polymers formed by the polymerization of propylene.

 

top of page