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Term Definition
Abrasion Resistance

Resistance to being worn away by rubbing or friction.

Absorption

The process by which a liquid or mixture of liquid and gases is drawn into the pores of a porous solid material.

Absporptivity

The relative ability to absorb sound and light.

Abutment Joint

A surface divider joint designed to allow free movement between new and existing construction or between different materials.

Accelerator

A substance, such as calcium chloride, added to a concrete mix to speed up its setting and strength development.

Access Flooring

A raised finish floor surface consisting entirely of small, individually removable panels beneath which wiring, ductwork, and other services may be installed.

Access Right

Right of an owner to have ingress and egress to and from a property.

Accessory Building

A building or structure on the same lot as the main or principal building.

Acoustical Ceiling

A ceiling of fibrous tiles that are highly absorbent of sound energy.

Acoustical Glass
A glazing unit used to reduce the transmission of sound through the glazed opening by bonding a soft interlayer between the layers of glass.
Acoustical Plaster
Calcined gypsum mixed with lightweight aggregates.
Acoustics

Science dealing with the production, control, transmission, reception and effects of sound, and the process of hearing.

Acrylic

A transparent thermoplastic made from esters of acrylic acid.

Active Pressure

The pressure exerted by retained earth against a retaining wall.

Additive

Materials mixed with a basic plastic resin to alter its properties.

Adhesion

The ability of a coating to stick to another surface.

Adhesive

A substance used to hold materials together by surface attachment.

Admixture

A prepared substance added to concrete to alter or achieve certain characteristics.

Adsorbant

A material that has the ability to cause molecules of gases, liquids, or solids to adhere to its surfaces without changing the adsorbent physically or chemically.

Aesthetics

The sudy or theory of beauty.

Agglomeration

A process that bonds ground iron-ore particles into pellets to facilitate handling.

Aggregate

Sand, gravel, crushed stone or other material that is a main constituent of Portland Cement, concrete and aggregated gypsum plaster. Also, polystyrene, perlite and vermiculite particles used in texture finishes.

Aggregate

Inert granules such as crushed stone, gravel, and expanded minerals mixed with Portland cement and sand to form concrete.

AIA

(1) The American Institute of Architects. Founded in 1857 and headquartered in Washington DC, the AIA offers resources for architects and is an advocate for the value of architecture.

Architects also use the AIA designation to indicate that they are both members of The American Institute of Architects and licensed to practice the profession.

(2) American Insurance Assn., successor to the National Board of Fire Underwriters and a nonprofit organization of insurance companies.

Air Entrainment

The incorporation of tiny air bubbles into concrete or mortar to improve its workability and resistance to freezing.

Air Gap

In plumbing, an unobstructed vertical distance between the lowest opening of any pipe that supplies a plumbing fixture and the level at which the fixture will overflow.

Air-Conditioning

The process of treating air to control simultaneously its humidity, cleanliness, and temperature and to provide distribution within a building.

Air-Dried Lumber

Wood dried by exposing it to air.

Air-Entrained Cement

A Portland cement with an admixture that causes a controlled quantity of stable, microscopic air bubbles to form in the concrete.

Air-Entrained Concrete

Concrete with an admixture added that produces millions of microscopic air bubbles in the concrete.

Air-Supported Structure

A membrane enclosing a pressurized occupied space, which must be held down to its foundation.

Airborne Sound

Sound traveling through the medium of air.

Alkyd

Synthetic resin modified with oil for good adhesion, gloss, color retention, and flexibility.

Allowable Stress

The maximum unit stress permissible in a structural member. Also referred to as working stress.

Alloy

A metallic material composed of two or more chemical elements one of which is a metal.

Aloying Element

Amu substance added to a molten metal to change its mechanical or physical properties.

Alternating Current

An electric current that varies periodically in value and direction by flowing first in one direction and then in the opposite direction.

Altitude

The angle that the sun makes with the horizon.

Alumina

A hydrated form of aluminum oxide from which aluminum is made.

Ambient Temperature

The temperature of the surrounding air.

Ampere

A basic SI unit that measures the rate of flow of electric current.

Anaerobic Bonding Agents

Bonding agents that set hard when not exposed to oxygen.

Anchor

Metal securing device embedded or driven into masonry, concrete, steel or wood.

Anchor Bolt

Heavy, threaded bolt embedded in the foundation to secure sill to foundation wall or bottom plate of exterior wall to concrete floor slab.

Angle of Repose

The angle of the sloped surface of the sides of an excavation.

Annealing

Heating a metal to a high temperature followed by controlled cooling to relieve internal stresses.

Annular Ring Nail

A deformed shank nail with improved holding qualities specially designed for use with gypsum board.

Anodizing

Am electrolytic process that forms a permanent, protective oxide coating on aluminum.

ANSI

American National Standards Institute, a nonprofit, national technical association that publishes standards covering definitions, test methods, recommended practices and specifications of materials. Formerly American Standards Assn. (ASA) and United States of America Standards Institute (USASI).

APA Performance-Rated Panels

Plywood manufactured to the structural specifications and standards of APA - The Engineered Wood Association.

Aquifer

An underground permeable material through which water flows.

Arc Resistance

The total elapsed time in seconds and electric current must arc to cause a part to fail.

Arch

A curved structure in which the internal stresses are essentially compression.

Architectural Terra Cotta

Clay masonry units made with a textured or sculptured face.

Area Separation Wall

Residential fire walls, usually with a 2- to 4-hour rating, designed to prevent spread of fire from an adjoining occupancy; extends from foundationGlossFoundation.1041 to or through the roof. Identified by codes as either "fire wall", "party wall" or "townhouse separation wall."

ASA

Formerly American Standards Assn., now American National Standards Institute (ANSI).

Asphalt

Dark brown to black hydro-carbon solids or semisolids having bituminous constituents that gradually liquify when heated.

ASTM

Formerly American Society for Testing and Materials, now ASTM, a nonprofit, national technical society that publishes definitions, standards, test methods, recommended installation practices and specifications for materials.

Attenuation

Reduction in sound level.

Autoclave

A high-pressure steam room that rapidly cures green concrete units.

Awning Window

A window that pivots near the top edge of the sash and projects toward the exterior.

Axial Load

A longitudinal load that acts at the centroid of a member and perpendicular to it's cross section.

Axminster Construction

Carpet formed by weaving on a loom that inserts each tuft of pile individually into the backing.

Azimuth

A horizontal angle measured clockwise from North or South.