AC-377 / ACCEPTANCE CRITERIA 377
AIR BARRIER ASSOCIATION OF AMERICA (ABAA)
AIR BARRIER SYSTEM
AIR-PURIFYING RESPIRATOR (APR)
ALTERNATIVE IGNITION BARRIER ASSEMBLY
ALTERNATIVE THERMAL BARRIER ASSEMBLY
ATTIC – VENTED
ATTIC – UNVENTED
A-SIDE: (A-Component) One component of a two-component system. For polyurethane foam and coatings, the ISOCYANATE component. (See ISOCYANATE.)
ABAA: See AIR BARRIER ASSOCIATION OF AMERICA.
ABSOLUTE HUMIDITY The actual concentration of water vapor in air. May be expressed in units of kPa, grains of moisture per pound of dry air, pounds of moisture per pound of dry air, or as a partial pressure as inches of mercury (in. Hg).
AC-377 / ACCEPTANCE CRITERIA 377: The standard to which a specific formulation of spray polyurethane foam (SPF) is evaluated by the International Code Council Evaluation Service (ICC-ES) in order to issue an Evaluation Report which describes the foam’s compliance with building code requirements.
ACCELERATOR A chemical additive to coating or polyurethane foam systems used in relatively small amounts to increase the speed of the reaction or to decrease the time required to cure or dry.
ACRYLICS: Resins resulting from the polymerization of derivatives of acrylic acids, including esters of acrylic acid, methacrylic acid, acrylonitrile, and their copolymers. They can be carried in a water or solvent solution, and they are film-forming materials.
AEROSOL: A suspension of fine solid particles or liquid droplets in a gas. In high-pressure foam and coating applications, liquid SPF chemicals and coating materials are formed into an aerosol in the spray gun by expulsion through a nozzle. (See ATOMIZATION.)
AGGREGATE: Any mineral surfacing material. May include crushed gravel, river-washed gravel, roofing granules, etc.
AGING: The effect on materials that are exposed to an environment for an interval of time.
AIR BARRIER ASSOCIATION OF AMERICA (ABAA): ABAA is an organization that promotes the use of air barriers; offers technical specifications to designers; and offers on-site inspections. It develops standards of proficiency in the industry through the ABAA On-Site Quality Assurance Program. ABAA offers training to installers, estimators, managers, and administrators on the contractor side, as well as AIA accredited courses for design professionals. Some types of SPF are recognized as an air-barrier material via product testing and certified contractors.
AIR IMPERMEABLE: An insulation having an air permanence at a specific thickness that is equal to or less than 0.02 L/s•m2 at 75 Pa pressure differential (0.004 ft3/ft2•min at 1.57 lb/ft2) tested in accordance with ASTM E 2178 or E 283.
AIR PERMEABLE: An insulation having an AIR PERMANENCE at a specific thickness that is greater than 0.02 L/s•m2 at 75 Pa pressure differential (0.004 ft3/ft2•min at 1.57 lb/ft2) tested in accordance with ASTM E 2178 or E 283. (See also PERMEABILITY, AIR and PERMEANCE, AIR.)
AIR-PURIFYING RESPIRATOR (APR): Respirators that consist of a facemask and an air-purifying device, which is either attached directly to the mask or carried on a body harness and connected to the mask via a breathing hose. APRs selectively remove specific airborne contaminants (particulate, vapors, fumes, and gases) from ambient air by filtration, adsorption, or chemical reactions. Filtering cartridges are removed and replaced at the end of their useful service life. APRs can be either of the full face or half mask varieties. (See RESPIRATOR.)
ALIPHATIC (POLYURETHANE): A type of polyurethane that does not contain carbon atoms arranged in aromatic (benzene) ring structures. As compared to AROMATIC (POLYURETHANE), coatings based on aliphatic polyurethane have superior resistance to UV weathering, and better color and gloss retention. (See also AROMATIC [POLYURETHANE].)
ALTERNATIVE IGNITION BARRIER ASSEMBLY: An assembly consisting of either the exposed SPF or the SPF with a fire-protective product that complies with the conditions of acceptance of Appendix X or for attic floors, complies with ASTM E970.
ALTERNATIVE THERMAL BARRIER ASSEMBLY: An assembly consisting of either the exposed SPF or the SPF with a fire-protective product that complies with the Special Approval section of the IBC or the Specific Approval section of the IRC. Referenced test procedures include NFPA 286, UL 1715, FM 4880 or UL 1040.
AMBIENT TEMPERATURE: The surrounding air temperature.
AMINE CATALYST: A broad range of nitrogen-based compounds that are used to promote blowing and curing reactions in polyurethanes. An amine catalyst is typically contained in the B-side, or resin, of the two-component polyurethane system.
APPLICATION RATE: The quantity (mass, volume, or thickness) of material applied per unit area.
AREA DIVIDER: A raised, flashed assembly (typically a single-wood 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). May be used to facilitate the installation of tapered insulation.
AROMATIC (POLYURETHANE): A type of polyurethane that contains some carbon atoms arranged in aromatic (benzene) ring structures. As compared to ALIPHATIC (POLYURETHANE), coatings based on aromatic polyurethane are usually tougher, but have less resistance to UV weathering, and less color and gloss retention. (See also ALIPHATIC [POLYURETHANE].)
ASPHALT: A dark brown to black bituminous substance, solid or semi-solid in consistency, obtained from petroleum refining. It consists mainly of hydrocarbons. Asphalt products are available for hot or cold application. Asphalt will dissolve in mineral spirits.
ASTM INTERNATIONAL: Formerly known as the American Society for Testing and Materials. A test standards development agency.
ATOMIZATION: The breakup of liquid or fluid into spray when forced through a small opening or orifice at high pressure.
ATTIC – VENTED: The unfinished space between the ceiling assembly of the top story and the roof assembly that has openings to the outside adequate to promote natural or mechanical air exchange.ATTIC – UNVENTED: The unfinished space between the ceiling assembly of the top story and the roof assembly that has no openings to the outside adequate to promote natural or mechanical air exchange.
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