» Access flooring A raised finish floor surface consisting of small, individually removable panels beneath which wiring, ductwork, and other building services may be installed.
» Acoustical ceiling A ceiling of fi brous tiles that are highly absorbent of sound energy.
» Acoustical Wall Partition - Acoustic systems, the highest specification movable wall available, are designed to cover every conceivable application where sound reduction is a
necessary criteria.
» Abutment joint A surface divider joint designed to allow free movement between new and existing construction or between differing materials.
» Accelerating admixture An admixture that causes concrete or mortar to cure more rapidly.
» Access standard A set of regulations ensuring that buildings are accessible and usable by physically handicapped members of the population.
» Acrylic A transparent plastic material widely used in sheet form for glazing windows and skylights.
» Active metal A metal relatively high on a galvanic series, tending to act as an anode in galvanic couples.
» Actual dimension The true dimension of a material, as distinct from its nominal dimension.
» (ADA) Airtight drywall approach.
» Admixture In a concrete or mortar, a substance other than cementitious material, water, and aggregates included in the mixture for the purpose of altering one or more
properties of the mixed material, either in its plastic working state or after it has hardened.
» Advanced framing techniques A wood light framing system that minimizes redundant framing members, reducing the amount of lumber required and increasing the thermal
effi ciency of the insulated frame.
» Aerogel A silicon-based foam used to fill the interstitial space in insulating glazing units.
» AESS Architecturally exposed structural steel.
» Aggregate Inert particles, such as sand, gravel, crushed stone, or expanded minerals, in a concrete, mortar, or plaster.
» Air barrier A material that reduces air leakage through a building assembly.
» Air barrier assembly An interconnected assemblage of materials that can effectively resist air pressure differentials acting across the boundary of a wall, roof, or
floor assembly.
» Air barrier system An interconnected collection of air barrier assemblies responsible for the overall air leakage performance of a completed building.
» Air-entraining admixture An admixture that causes a controlled quantity of stable microscopic air bubbles to form in concrete or mortar during mixing, usually for the purposes
of increasing workability and resistance to freeze-thaw conditions.
» Air permeance A measure of a material's permeability to airfl ow. A low air permeance is a desirable characteristic of an air barrier material.
» Air-supported structure A structure, usually long-span, with a fabric roof supported by an increase in air pressure inside the structure.
» Airtight drywall approach (ADA) An air barrier system relying on gypsum board interior finish and the sealing of joints between framing members of a light frame building,
serving to reduce the flow of air through the exterior walls and roof.
Air-to-air heat exchanger A device that exhausts air from a building while recovering much of the heat from the exhausted air and transferring it to the incoming air.
» Alloy A substance composed of two or more metals or of a metal and a nonmetallic constituent.
» Aluminum A silver-colored, nonferrous metal that naturally forms a self-protecting oxide layer.
» Anchorage The device that fastens the end of a posttensioning tendon to the end of a concrete slab or beam.
» Anchor bolt A bolt embedded in concrete for the purpose of fastening a building frame to a concrete or masonry foundation.
» Angle A structural section of steel or aluminum whose profi le resembles the letter L.
» Angle of repose The steepest angle at which an excavation may be sloped so that the soil will not slide back into the hole.
» Anneale Cooled under controlled conditions to minimize internal stresses.
» Anode The metal in a galvanic couple that experiences accelerated corrosion.
» Anodizing An electrolytic process that forms a permanent protective oxide coating on aluminum, with or without added color.
» ANSI American National Standards Institute, an organization that fosters the establishment of voluntary industrial standards.
» Anticlastic Saddle-shaped or having curvature in two opposing directions
» APP See Atactic polypropylene.
» Appearance grading The grading of wood for its appearance properties, as distinct from its structural properties; not to be confused with visual grading.
» Apron The finish piece that covers the joint between a window stool and the wall finish below.
» Arch A structural device that supports a vertical load by translating it into axial inclined forces at its supports.
» Architectural concrete Concrete intended as a fi nish surface and produced to a higher-quality standard.
» Architectural sheet metal roofing A roof covering made up of sheets of metal in a traditional shop- or site-fabricated pattern such as standing seam, fl at seam, or batten
seam.
» Architecturally exposed structural steel Structural steel intended to be left exposed in the fi nished building and fabricated and installed to a higher-quality standard.
Architectural Woodwork Institute - A trade organization that develops standards for custom millwork.
» Arc welding A process of joining two pieces of metal by melting them together at their interface with a continuous electric spark and adding a controlled additional amount of
molten metal from a metallic electrode.
» Area divider A curb used to partition a large roof membrane into smaller areas to allow for expansion and contraction in the deck and membrane.
» Articulation class (AC) A measure of a finish ceiling's absorption and refl ection of sound, particularly with regard to speech clarity in an open office environment.
» Ash dump A door in the underfi re of a fi replace that permits ashes from the fire to be swept into a chamber beneath, from which they may be removed at a later time.
» Ashlar Squared stonework.
» Asphalt A tarry brown or black mixture of hydrocarbons; one type of bitumen.
» Asphalt roll roofing A continuous sheet of the same roofing material used in asphalt shingles. See Asphalt shingle.
» Asphalt-saturated felt A water-resistive sheet material, available in several different thicknesses, usually consisting of matted cellulose fi bers that have been impregnated
with asphalt; used to provide a protective layer in an exterior wall or roof assembly; also called building felt.
» Asphalt shingle A roofi ng unit composed of a heavy organic or inorganic felt saturated with asphalt and faced with mineral granules.
» Atactic polypropylene (APP) An amorphous form of polypropylene used as a modifier in modified bitumen roofing.
» Auger A helical tool for creating cylindrical holes.
» Autoclaved aerated concrete (AAC) Concrete formulated so as to contain a large
percentage of gas bubbles as a result of a chemical reaction that takes place in an
atmosphere of steam.
» Architectural Woodwork Institute. Awning window A window that pivots on a horizontal axis at the top edge of the sash and projects toward the outdoors.
» Axial In a direction parallel to the long axis of a structural member.
