This glossary contains many useful terms and definitions that will help you understand much of the work we do at ROOFCORP.

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Abrasion resistance: the ability to resist being worn away by contact with another moving, abrasive surface, such as foot traffic, mechanical equipment, wind-blown particles, etc.

Absorption: the ability of a material to accept within its body, quantities of gases or liquid, such as moisture.

Accelerated weathering: the exposure of a specimen to a specified test environment for a specified time with the intent of producing in a shorter time period, effects similar to actual weathering.

Acid etch: in waterproofing, the use of a strong acid to remove the surface of concrete to expose the aggregate.

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

Acrylic resin: polymers of acrylic or methacrylic monomers. Often used as a latex base for coating systems.

Active metal (anodic): a metal or material that readily gives up electrons to a cathodic (noble) material. (See anodic). An active metal will corrode in the presence of moisture when in contact with a cathodic metal.

Adhesion: steady or firm attachment.

Adhesive bond break: a material to facilitate independent movement between two units that would otherwise bond together.

Aggregate: (1) crushed stone, crushed slag or water-worn gravel used for surfacing a built-up roof system; (2) any granular material.

Aged R-value: thermal resistance value established by utilizing artificial conditioning procedures for a prescribed time period.

Air leakage: the unintended movement of air from a location where it is intended to be contained to another location.

Alligatoring: the cracking of the surfacing bitumen on a bituminous roof or coating on a SPF roof, producing a pat-tern of cracks similar to an alligator's hide; the cracks may not extend completely through the surfacing bitumen or coating.

Aluminized steel: sheet steel with a thin aluminum coating bonded to the surface to enhance weathering characteristics.

Aluminum: a nonrusting, malleable metal sometimes used for metal roofing and flashing. Anodic: a metal or material that readily gives up electrons to a cathodic material in the presence of an electrolyte (see Galvanic series).

ANSI: American National Standards Institute. Anticapillary hem: a hem used in a metal panel seam to reduce the potential for water migration.

APA: American Plywood Association.

APC: American Plastics Council.

APP: see Atactic polypropylene.

Application rate: the average quantity (mass, volume or thickness) of material applied per unit area.

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

APC/SPFA: American Plastics Council/Spray Polyurethane Foam Alliance.

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: an asphalt 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 accommodate thermal stresses in a roof system where an expansion joint is not required, or to separate large roof areas or separate roof systems comprised of different/incompatible materials, and may be used to facilitate installation of tapered insulation.

ARMA: Asphalt Roofing Manufacturers Association.

Area practices: design or application techniques peculiar to a specific geographical region.

Asbestos: a group of natural, fibrous, impure silicate materials.

ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers.

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, Air blown: asphalt produced by blowing air through molten asphalt to raise its softening point and modify other properties.

Asphalt emulsion: a mixture of asphalt particles and emulsifying agent, such as bentonite clay and water.

Asphalt felt: an asphalt-saturated and/or 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. Classified by ASTM Standard D 2822-1 Asphalt Roof Cement, and D 4586-2 Asphalt Roof Cement, Asbestos-Free, Types I and II. Type I is sometimes referred to as "plastic cement," and is made from asphalt characterized as self-sealing, adhesive and ductile, and conforming to ASTM Specification D 312, Type I; Specification D 449, Types I or II; or Specification D 946 (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, and conforming to the requirement of ASTM Specification D 312, Types II or III; or Specification D 449, Type III. (see Plastic cement and Flashing cement.)

Asphalt shingle: a shingle manufactured by coating a reinforcing material (felt or fibrous glass mat) with asphalt and having mineral granules on the side exposed to the weather. (see Shingle)

Asphaltene: a high molecular weight hydrocarbon fraction precipitated from asphalt by a designated solvent (paraffinic naphtha) 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 cavity or open space above the ceiling and immediately under the roof deck of a steep-sloped roof.