ACTUAL AGE:
As opposed to effective age. The actual age of a building is the objective age in years measured simply by the passage of time since it was constructed. Effective age is a subjective measurement of the condition of a building, influenced mostly by the maintenance and upkeep carried out on the building over the years.

AESTHETIC VALUE:
A subjective element in the overall market value of a property created by the physical presentation of the land or buildings.

AGGREGATE:
Sand and stone that is mixed into concrete to create a concrete aggregate mixture.

AIR-DRIED LUMBER: As opposed to kiln-dried lumber.
Lumber that has been allowed to dry over time by leaving it out in the open. Often has a higher moisture content than other types of lumber. As opposed to kiln-dried lumber which has a lower moisture content and thus tends not to warp as much after installation. See "KILN-DRIED LUMBER".

AIRWAY:
The space between a ceiling's insulation and the roof boards that allows air movement through the roofing system's vents, allowing moisture and summer heat buildup to escape.

ATTACHED HOUSING:
Duplex, triplex, row housing, or townhouses. Two or more dwellings that are attached physically but are owned and/or occupied by different people.

ATTIC ACCESS:
Also known as a scuttle. An opening in the ceiling giving access to an unfinished attic area.

AWNING WINDOW:
A window with a single section hinged at the top that opens outward.