A/C - An abbreviation for air conditioner or air conditioning.

A/C Condenser - The outside fan unit of the Air Conditioning system. It removes the heat from the freon gas and "turns" the gas back into a liquid and pumps the liquid back to the coil in the furnace.

A/C Disconnect - The main electrical ON-OFF switch near the A/C Condenser.
Aerator The round-screened screw-on tip of a sink spout. It mixes water and air for a smooth flow.

Aggregate - A mixture of sand and stone and a major component of concrete.

Air-dried Lumber - Lumber that has been piled in yards, or sheds for any length of time. For the United States as a whole, the minimum moisture content of thoroughly air-dried lumber is 12 to 15 percent and the average is somewhat higher. In the South, air-dried lumber may be no lower than 19 percent.

Air Space - The area between insulation facing and interior of exterior wall coverings.
Normally a one-inch air gap.

Airway - A space between roof insulation and roof boards for movement of air.

Alligatoring - Coarse, checking pattern characterized by a slipping of the new paint coating over the old coating to the extent that the old coating can be seen through the fissures.

Allowance(s) - A sum of money set aside in the construction contract for items, which have not been selected and specified in the construction contract. For example, selection of tile as flooring may require an allowance for an under-payment material, or an electrical allowance, which sets aside an amount of money to be spent on electrical fixtures.

Anchor Bolts - Bolts to secure a wooden sill plate to concrete, or masonry floor or wall.

Apron - The flat member, of the inside trims, of a window placed against the wall immediately beneath the stool.

Architect - One who has completed a course of study in building and design, and is licensed by the state as an architect. One who draws up plans.

Area Wells Corrugated metal or concrete barrier walls installed around a basement window to hold back the earth

Areaway - An open sub-surface space adjacent to a building used to admit light or air or as a means of access to a basement.

Asphalt - Most native asphalt is a residue from evaporated petroleum. Used widely in building for waterproofing roof coverings of many types, exterior wall coverings, flooring tile, and the like.

Astragal - A molding, attached to one of a pair of swinging doors, against which the other door strikes.

Attic Ventilators - In houses, screened openings provided to ventilate an attic space. They can also consist of power-driven fans used as an exhaust system.
(See also Louver.)