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

Any construction or renovation to an existing structure other than repair or addition that requires a permit. Also, a change in a mechanical system that involves an extension, addition or change to the arrangement, type or purpose of the original installation that requires a permit.

The temperature of the surrounding air.

The angle that the sun makes with the horizon.

Aisle round an apse.

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

Window with wood construction covered with aluminum sheet. Has a factory-applied finish to protect from weather and solar degradation.

Steel coated with aluminum for corrosion resistance.

Mechanism used in Bid Documents to seek separate bids for a different design than the "Base Bid" design. May be "Additive" or "Deductive" alternates.

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).

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

A paint composed of a chemically synthesized, alkyd derived base, thinned with mineral spirits. The current version of "oil" based paints.

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

The typical effect produced by a wall covering. A pattern in which the units of design are evenly distributed over a surface, without undue emphasis.

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

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.

Alkylphenols are a large family of organic compounds used in a wide variety of products, including cleaning products, beauty products, contraceptives, coatings, fragrances, thermoplastics, carbonless copy paper, and agrochemicals. Most concerns are focused on alkylphenol ethoxylates (APEs), which bioaccumulate and have been shown to cause endocrine disruption in fish. They are in cleaning products that end up in waterways from wastewater treatment effluent. Some alkylphenols, especially nonylphenol, are being phased out in Europe and more research into their impacts is needed. A few governments with environmentally preferable purchasing programs restrict or ban APEs. https://healthymaterialslab.org/tool-guides/hml-resources

Anything that causes an allergic reaction, such as pollen, dust mites, or animal dander (skin protein that flakes off). https://healthymaterialslab.org/tool-guides/hml-resources

Walkway along the top of a wall.

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 underlayment material, or an electrical allowance which sets aside an amount of money to be spent on electrical fixtures.