Absorption: The act or process of retaining foreign particles such as gas or liquid without transmission of these particles.
Acid Etch: (1) The use of a strong acid to remove the surface of concrete thereby exposing the aggregate. (2) The use of a strong acid to etch the surface of material such as metal in order for that material to accept a primer or Spray Polyurethane Foam.
Acrylic Coating: A coating system with an acrylic resin base.
Acrylic Resin: Polymers of acrylic or methacrylic monomers often used as a latex base for coating systems.
Active: Will corrode in the presence of moisture or a "noble" metal.
Adhere: The clinging of one surface to another; either molecularly or otherwise.
Adhesion: The state of adhering
Aggregate: A surfacing or ballast for a roof system. Aggregate can be rock, stone, crushed stone or slag, water-worn gravel, crushed lava rock or marble chips.
AIA: American Institute of Architects
Air Blown Asphalt: Asphalt produced by blowing air through molten asphalt held at an elevated temperature. This procedure is used to modify properties of the asphalt.
Alligatoring: The cracking of the surface bitumen on a built-up roof, producing a pattern of cracks that resemble an alligators skin.
Aluminized Steel: Sheet steel with a thin aluminum coating on the surface to enhance the steels ability to withstand weathering.
Aluminum: A non-rusting metal sometimes utilized in the fabrication of metal roofing, gutters and roof flashings.
Ambient Temperature: The temperature of the air.
Anodic: When two metals are connected in an electrolyte, they will form a galvanic cell, with the higher metal in the galvanic series being the anode. The anodic will oxidize and produce an electrical current which protects the cathode from corrosion.
ANSI: American National Standards Institute
APA: American Plywood Association
APP: See "Atactic Polypropylene"
Application Rate: The rate at which a material is applied per unit area.
Architectural Panel: A metal roof panel that usually requires solid decking underneath.
Architectural Shingle: Shingle that provides a dimensional appearance. See also Dimensional Shingle or Laminated Shingle.
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.
ARMA: Asphalt Roofing Manufacturers Association
Asbestos: An incombustible fibrous mineral form of magnesium silicate formerly used for fireproofing and sometimes used for the reinforcement of roofing materials.
ASHRAE: American Society of Heating, Refrigerating & Air-Conditioning Engineers, Inc.
Asphalt: A dark brown to black cementitious material in which the predominating constituents are bitumens, which occur in nature or are obtained in petroleum processing. Asphalt can be refined to conform to various roofing grade specifications:
Asphalt Emulsion: A mixture of asphalt particles and an emulsifying agent such as bentonite clay and water.
Asphalt Felt: An asphalt-saturated and/or an asphalt-coated felt membrane. (See also "Felt")
Asphalt Mastic: A mixture of asphaltic material and graded mineral aggregate that can be poured when heated but requires mechanical manipulation to apply when cool.
Asphalt Primer: See "Primer"
Asphalt Roof Cement: The proper name for Plastic Cement and Flashing Cement. Asphalt roof cement consists of solvent-based bitumen, mineral stabilizers, and other fibers (sometimes asbestos). Asphalt roof cement is categorized by ASTM standard D 2822-91 (1997) or for non-asbestos, ASTM standard D 4586-93.
Asphaltene: A high molecular weight hydrocarbon fraction precipitated from asphalt by a designated paraffinic naphtha solvent at a specified temperature and solvent asphalt ratio.
ASTM: American Society for Testing and Materials
Atactic Polypropylene: A group of high molecular weight polymers formed by the polymerization of propylene.
Attic: The open area above the ceiling and under the roof deck of a steep-sloped roof.
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