Alabaster 
Usually used for carved ornaments, this is a fine-grained gypsum. 

Alarm Check Valve 
Check valve, which is located in the riser of a wet pipe fire sprinkler system and sounds an alarm when water begins flowing through it. 

Alcove 
A section of a room, such as a breakfast nook, which is recessed. 

Alette 
Building wing or a buttress. 

Alias 
Another name by which a person is known; synonymous with AKA. 

Alidade 
Upper part of a transit or a telescopic instrument used to take bearings. 

Alien 
Foreign-born individual who is not a citizen of the country in which he/she resides. Aliens in the United States have the full legal protection and rights as citizens. 

Alienation 
Voluntary conveyance of a property from one person to another by means of transfer of title and possession. 

Alienation Clause 
A mortgage provision requiring that the balance of that loan be repaid in full if the property is sold or transferred. 

Align 
To bring into a straight line. 

Aligned Section 
A cut-away view, as it would look if part of the exterior were removed, into the interior of an object or building. Shown on a drawing and lined up with the full view from which is taken. 

Aliphatic Glue 
Yellow wood glue that is strong but not waterproof. 

Alkali 
Mineral salt found in soil. Chemical base in concrete and mortar, such as soluble salts. Alkalis may be present in concrete and can lead to expansion and cracking when brought in contact with aggregate. Alkalis can also interfere with paint application, making it necessary to wait 60 or more days before painting, so that all of the alkalis have emerged from the concrete and are able to be cleaned off. If painted prior to this, the alkalis will migrate to the surface and drive off the paint 

Alkaline Soil 
Soil containing a higher concentration of mineral salt than natural acid. 

Alkyd 
Thermoplastic or synthetic resin used in making paint and other coatings. Used in both interior and exterior pain, it is solvent-thinned. Prior to the development of alkyds, around World War II, linseed oil was the basis for paint. Alkyd based paints cover better, resist chalking and mildew, dry faster and withstand sunlight better. Alkyd based paint has an alkyd resin base and is different from oil based paint, which has a linseed oil base. At times, linseed oil and alkyds are blended together in paint. 

Alkyd Binder 
Used to speed up the drying process by reacting to oxygen in the air, this oil-modified phthalate resin is used in paint. 

Allegation 
A charge, claim, accusation or statement of a party to an action against a respondent. The allegation establishes the circumstances to be proved in a formal action before the court. 

Allen Screw 
Screw or bolt with a hexagonal socket in its head. see also Allen Wrench.

Allen Wrench 
Rod, with one part bent at a right angle to provide leverage, it has a hexagonal cross section designed to fit a hex socket or Allen screw. 

Alley 
Narrow street that provides access to the rear of buildings by going through the middle of a block. A narrow street, walk or lane between two rows of buildings. 

Alligator 
Term for dried paint that has cracked making it take on the appearance of alligator skin, this usually occurs when paint is applied to a glossy painted surface without first scuff-sanding to promote adhesion. Also happens when a too soft primer is used under a finish coat or enough time has not been allowed between coats of paint. Also refers to asphalt to coating, which has cracked because a poor base was laid. 

Alligator Clip 
Clip, which is spring-loaded with alligator-like jaws, is used to make temporary connections in an electrical circuit or used to hold small objects. 

Alligatoring 
The cracking in paint that results in a coarse pattern, resembling alligator skin. 

All-Inclusive Trust Deed 
A mortgage (trust deed) that encompasses all existing mortgages and is subordinate to them. 

Allocation Method 
Approach used to allocate the price, which is paid for two or more properties and is based on their fair market value rather than appraised value. 

Allodium 
Piece of property that is owned outright with nothing due to another party. 

Allotment 
Apportionment. Allocation of real estate made on an equitable basis to prospective buyers. 

Allowable Span 
Span is the distance between structural supports. Allowable span is the maximum distance permitted that a structural member may span between supports. 

Allowable Stress 
The maximum permissible stress that is permitted to be placed safely on a structural member or pressure-retaining component. This is determined through testing and varies specifically with the material in question. 

Allowance 
Amount of money offered by builders of new homes, to be applied toward the cost of items subject to customer selection, such as lighting fixtures or carpeting. 

Allowance for Vacancy and Income Loss 
When valuing income-producing property, allowance must be made for the income lost from unoccupied premises. 

Alloy 
Mixture of two or more metals or of a metal and/or other elements to improve certain qualities of the material to be produced from the alloy. 

All-Purpose Joint Compound 
Used for setting tape and covering joints and fasteners, it is a combination of drywall joint and a topping compound. Premixed or packaged as a dry powder to be mixed with water, it has many of the smooth-spreading qualities of topping compound but has greater adhesion. 

Alluvial 
Soil, sand and gravel, which is deposited on land, usually at a shoreline, as the result of flooding or tidal action. The resulting land is normally retained by the owner. 

Alluvial Fan 
Usually seen at a junction where a small stream joins a larger one or at the point where water flows through a narrow gorge that opens onto a plain, this fan-shaped deposit of soil is left behind. 

Alluvion 
The gradual increase of land being deposited along the shore and caused by deposits from upstream. 

Alluvium
Soil, sand and gravel, which is deposited on land, usually at a shoreline, as the result of flooding or tidal action. The resulting land is normally retained by the owner. 

All-Weather Wood Foundation 
Place directly on a gravel base, the building foundation is built from pressure-treated wood. 

Allyl Resin 
A thermosetting resin that can be heated only one time and then is cooled into a temperature resistant solid to be used in laminate adhesives. 

Alnico 
Iron, aluminum, nickel and cobalt made into a permanent-magnet alloy. 

ALS Cable
see Aluminum Sheathed Cable. 

Alta Title Policy 
American Land Title Association policy. see also American Land Title Association.

Alteration 
Changes or modifications to a building or structure.

Alternate Power Source 
Back-up electrical power, usually provided by a generator, to be used if the normal power supply fails. 

Alternating Current (AC) 
An electric current that reverses its direction periodically.

Alternative Mortgage 
A loan that is other than the standard fixed-rate mortgage, i.e. a non-conforming loan. An alternative mortgage may vary in interest rate, maximum loan amount, or loan-to-value ratio.

Alternator 
Electric generator or dynamo producing alternating current, which is an electric current that reverses its direction periodically. 

Aluminum 
A chemical element. Rustproof, non-magnetic, silver-white lightweight metal, which is a good thermal and electrical conductor. It is abundant in the earth's crust. The atomic symbol is AL, atomic number is 13 and its atomic weight is 26.98. 

Aluminum Nails 
Used in places where other metals might corrode, such as fastening aluminum siding in place, these nails are lightweight, corrosion-resistant and made in a variety of shapes and sizes. 

Aluminum Oxide 
Abrasive used for grinding and polishing. 

Aluminum Panel Nails 
Designed for use with aluminum, they have a large diameter head and an elastomer gasket or washer under the head. 

Aluminum Sheathed Cable (ALS Cable) 
Individually insulated electrical conductors in close-fitting aluminum tubing. 

Aluminum Siding 
Metal siding, which can be used, instead of shingles, or placed over existing wood siding. Aluminum siding does not require painting. 

Aluminum-clad Windows 
Windows with aluminum coating over wood.