A

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

A/C circuit Alternating Current. The flow of current through a conductor first in one direction, then in reverse. It is used exclusively in residential and commercial wiring because it provides greater flexibility in voltage selection and simplicity of equipment design.

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.

above grade wall A wall more that is mostly above grade and enclosing conditioned space.

ABS (acrylonitrile butadiene styrene) Rigid black plastic pipe used only for drain lines.

absolute humidity Amount of moisture in the air, indicated in grains per cubic foot.

accelerator Any material added to stucco, plaster or mortar which speeds up the natural set.

access That which enables a device, appliance or equipment to be reached.

access panel An opening in the wall or ceiling near the fixture that allows access for servicing the plumbing/electrical system.

accessibility Level of access a building offers people with disabilities.

accessible Can be approached or entered by the inspector safely, without difficulty, fear or danger.

accessory structure An additional building to the primary building.

acre 43,560 square feet.

acrylic A glassy thermoplastic material that is vacuum-formed to cast and mold shapes that form the surface of fiberglass bathtubs, whirlpools, shower bases, and shower stalls.

activate To turn on, supply power, or enable systems, equipment, or devices to become active by normal operating controls. Examples include turning on the gas or water supply valves to the fixtures and appliances and activating electrical breakers or fuses.

actual dimension (lumber) The exact measurement of lumber after it has been cut, dried and milled.

actual knowledge The knowledge possessed by an individual as opposed to that discovered through document review.

adaptor A fitting that unites different types of pipe together, e.g. ABS to cast iron pipe.

addition An extension or increase in the conditioned space of a building.

adhesion The property of a coating or sealant to bond to the surface to which it is applied.

adhesive failure Loss of bond of a coating or sealant from the surface to which it is applied.

adverse conditions Conditions that may be dangerous for the inspector and may limit the walk-through survey portion of the inspection.

adversely affect Constitute, or potentially constitute, a negative or destructive impact.

aerator An apparatus that mixes air into flowing water. It is screwed onto the end of a faucet spout to help reduce splashing.

aggregate Crushed stone, slag or water-worn gravel that comes in a wide range of sizes which is used to surface built-up roofs.

air chamber A vertical, air-filled pipe that prevents water hammer by absorbing pressure when water is shut off at a faucet or valve.

air duct Ducts, usually made of sheet metal, that carry cooled or heated air to all rooms.

air filters Adhesive filters made of metal or various fibers that are coated with an adhesive liquid to which particles of lint and dust adhere. These filters will remove as much as 90% of the dirt if they do not become clogged. The more common filters are of the throwaway or disposable type.

air infiltration The amount of air leaking in and out of a building through cracks in walls, windows and doors.

air intake An opening in a building's envelope whose purpose is to allow outside air to be drawn in to replace inside air.

air space The area between insulation facing and interior of exterior wall coverings. Normally a 1" air gap.

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.

airway A space between roof insulation and roof boards provided for movement of air.

aisle An exit access component that provides a path of egress travel.

alarm signal A signal indicating an emergency, such as a fire, requiring immediate action.

alarm system Warning devices, installed or free-standing, including but not limited to: carbon monoxide detectors, flue gas and other spillage detectors, security equipment, ejector pumps and smoke alarms.

algae Microorganisms that may grow to colonies in damp environments, including certain rooftops. They can discolor shingles. Often described as "fungus."

alligatoring Extensive surface cracking in a pattern that resembles the hide of an alligator.

allowable span The distance between two supporting points for load bearing lumber such as joists, rafters or a girder.

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. Best kept to a minimum number and used for items whose choice will not impact earlier stages of the construction. For example, selection of tile because flooring may require an alternative framing or underlayment material. (Also, money that your parents give you as a child.)

alteration Any construction or renovation to an existing structure other than a repair or addition. Also, a change in a mechanical system.

aluminum wire A conductor made of aluminum for carrying electricity. Aluminum is generally limited to the larger wire sizes. Due to its lower conductivity, aluminum wire smaller than No. 12 is not made. Aluminum is lighter and less expensive than copper, but does not conduct as well. It also breaks easily.

amortization A payment plan by which a loan is reduced through monthly payments of principal and interest.

ampacity Refers to the how much current a wire can safely carry. For example, a 12 gauge electrical copper wire can safely carry up to 20 amps.

amperage The rate of flow of electricity through wire - measured in terms of amperes.

amps (AMPERES) The rate at which electricity flows through a conductor.

anchor bolts In residential construction, bolts used to secure a wooden sill plate to a concrete or masonry floor or wall. In commercial construction, bolts which fasten columns, girders or other members to concrete or masonry such as bolts used to anchor sills to masonry foundation.

angle iron A piece of iron that forms a right angle and is used to span openings and support masonry at the openings. In brick veneer, they are used to secure the veneer to the foundation. Also known as shelf angle.

angle stop A shutoff valve in which the inlet connects to the water supply pipe in the wall and the outlet angles 90 degrees upward toward the faucet or toilet.

annealing In the manufacturing of float glass, the process of controlled cooling done in a Lahr to prevent residual stresses in the glass. Re-annealing is the process of removing objectionable stresses in glass by re-heating to a suitable temperature followed by controlled cooling.

annual percentage rate (APR) Annual cost of credit over the life of a loan, including interest, service charges, points, loan fees, mortgage insurance, and other items.

anti-scald A valve that restricts water flow to help prevent burn injuries. See Pressure Balancing Valve and Thermostatic Valve. In some areas, plumbing codes require anti-scald valves. Speak to a professional in your area for more information and help with code requirements.

anti-siphon A device that prevents waste water from being drawn back into supply lines and possibly contaminating the water supply.

anti-walk blocks Elastomeric blocks that limit lateral glass movement in the glazing channel which may result from thermal, seismic, wind load effects, building movement, and other forces that may apply.

antiquated No longer in use, useful or functioning, as in most home inspection associations. Obsolete.

APA plywood (APA=American Plywood Association) Plywood that has been rated by the American Plywood Association. For example, number one APA rated exterior plywood contains no voids between laminate layers.

aperature The opening in pipes.

appliance A household device operated by use of electricity or gas. Not included in this definition are components covered under central heating, central cooling or plumbing.

appraisal An expert valuation of property.

approach The area between the sidewalk and the street that leads to a driveway or the transition from the street as you approach a driveway.

approve Acceptable to the authority having jurisdiction. Also, accepted by an internationally recognized organization such as InterNACHI.

apron A trim board that is installed beneath a window sill.

arbitration service A service to resolve complaints, as in NACHI's Arbitration Service.

arc-fault circuit interrupter A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and by functioning to de-energize the circuit when an arc fault is detected.

architect A tradesman who designs and produces plans for buildings, often overseeing the building process.

architects rule (ruler) Three sided ruler with different scales on each side. Also referred to as a "scale."

architectural service Any practice involving the art and science of building design for construction of any structure or grouping of structures and the use of space within and surrounding the structures or the design, design development, preparation of construction contract documents, and administration of the construction contract.

area wells Corrugated metal or concrete barrier walls installed around a basement window to hold back the earth.

areaway An open subsurface space around a basement window or doorwayy; provides light, ventilation, and access.

asbestos A common form of magnesium silicate which was used in various construction products due to its stability and resistance to fire. Asbestos exposure (caused by inhaling loose asbestos fibers) is associated with various forms of lung disease. The name given to certain inorganic minerals when they occur in fibrous form. Though fire-resistant, its extremely fine fibers are easily inhaled, and exposure to them over a period of years has been linked to cancers of the lung or lung-cavity lining and to asbestosis a severe lung impairment. A naturally occurring mineral fiber sometimes found in older homes. It is hazardous to your health when a possibility exists of exposure to inhalable fibers. Homeowners should be alert for friable (readily crumbled, brittle) asbestos and always seek professional advice in dealing with it.

asphalt A dark brown to black highly viscous hydrocarbon produced from the residue left after the distillation of petroleum. Asphalt is used on roofs and highways as a waterproofing agent.

asphalt plastic cement An asphalt-based cement used to bond roofing materials.

assessment A tax levied on a property, or a value placed on the worth of a property.

associate member An indentured servant. Beginning level of inspection association membership. Slave. See Candidate.

astragal A molding which is attached to one of a pair of swinging doors against which the other door strikes.

attic access An opening that is placed in the dry-walled ceiling of a home providing access to the attic.

attic ventilators In houses, screened openings provided to ventilate an attic space. They are located in the soffit area as inlet ventilators and in the gable end or along the ridge as outlet ventilators. They can also consist of power-driven fans used as an exhaust system.

auger In carpentry, a wood-boring tool used by a carpenter to bore holes.

authority having jurisdiction (AHJ) An organization, office, or individual responsible for enforcing the requirements of a code or standard, or for approving equipment, materials, an installation, or a procedure. The AHJ is often the building owner, health department, insurance agent, or fire Marshall.

automatic That which provides a function without the necessity of human intervention.

automatic fire-extinguishing system A system of devices and equipment which automatically detects a fire and discharges in an attempt to put it out.

automatic sprinkler system An automated sprinkler system for fire protection purposes.

awning window A window with hinges at the top allowing it to open out and up.