Glossary

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A/C (AC): Abbreviation for air conditioner and air conditioning.

A/C circuit: Alternating current, which is the flow of electrical 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 that removes the heat from the Freon® gas and turns the gas back into a liquid, then 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 that is mostly above grade and encloses conditioned space.

ABS: Acronym for 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 that speeds up the natural set.

access panel: A closure device or door used to cover an opening into a duct, wall, ceiling or enclosure near a fixture that allows access for servicing, such as for the plumbing or electrical system.

accessibility: The level of access that a building offers people with disabilities.

accessible: In the opinion of the inspector, can be approached or entered safely, without difficulty, fear or danger.

accessory structure: A building on a property in addition to the primary building.

accredited: Approved by an accrediting agency or state authority as meeting a prescribed standard, which describes InterNACHI's online and video training courses.

acre: An area equal to 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, whirlpool bathtubs, shower bases, and shower stalls.

activate: To turn on, supply power to, 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 or information possessed by an individual, as opposed to that discovered through document review. Persons with actual knowledge are likely to be interviewed for the research portion of a commercial property inspection.

ADA (Americans with Disabilities Act): Federal U.S. legislation enacted in 1990 to provide for, among other rights, physical access for disabled persons to public accommodations and commercial facilities, mandated in new construction and requiring retrofitting for existing buildings.

adaptor: A fitting that unites different types or materials of pipe, such as 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 that allows it 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 was applied.

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

adversely affect: To constitute, or potentially constitute, a negative or destructive impact.

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

AFCI (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.

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

AHJ (authority having jurisdiction): 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 may be the building owner, health department, building code officer, municipal inspector, building department, or fire marshal.

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

air duct: Ducts typically 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. Air filters remove as much as 90% of dirt if they do not become clogged. The more common filters are of the disposable type.

air gap (drainage): The unobstructed vertical distance through free atmosphere between the outlet of the waste pipe and the flood-level rim of the receptacle into which the waste pipe is discharged.

air gap (water distribution): The unobstructed vertical distance through free atmosphere between the lowest opening from any pipe or faucet that supplies water to a receptacle (sink, tank, fixture, or other device) and the flood-level rim of that receptacle.

air handler: Components that blow air through ductwork for heating, cooling and/or ventilation purposes.

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: A 1-inch air gap left between insulation facing and the interior of exterior wall coverings.

air-admittance valve: Pressure-activated, one-way mechanical vent that is used when venting through the building’s roof structure is not available.

air-dried lumber: Lumber that has been piled in yards or sheds for any length of time. Generally, for the United States, the minimum moisture content of thoroughly air-dried lumber is 12 to 15%, and the average is somewhat higher. In the South, air-dried lumber for use in home construction may be no lower than 19%.

airway: A space between roof insulation and roof boards that is provided to facilitate air movement.

aisle: A narrow passageway that provides a path for access and egress.

alarm signal: A signal indicating an emergency that requires immediate action, such as a fire.

alarm system: Installed or freestanding warning devices, including, but not limited to: carbon-monoxide detectors, flue-gas and other spillage detectors, security equipment, ejector pumps, and smoke alarms.

algae: Micro-organisms, sometimes referred to as fungus, that may grow into colonies in damp environments, including on certain types of rooftops and in certain environments. Algae can discolor shingles.

alligatoring: An oxidized condition of paint or aged asphalt that has lost its volatile oils due to exposure to sun and solar radiation, which is the ultimate result of the paint or asphalt's limited tolerance to thermal expansion and contraction. Alligatoring is characterized by a coarse, checked pattern that results when a new paint coating slips over the old coating to the extent that the old coating can be seen through the fissures, producing a pattern of cracks resembling an alligator hide.

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 a construction contract for items that, at the time of contract execution, have not been selected and specified. Allowances are best kept to a minimum number and used for items whose choice will not impact early stages of construction, such as the selection of tile (because the flooring may require an alternative framing or underlayment material).

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

amortization: A repayment plan by which a loan is reduced through regular (usually monthly) payments of principal and interest.

amp (ampere): The rate at which electricity flows through a conductor.

ampacity: Refers to 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.

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

angle iron: Also known as a shelf angle, 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.

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 lehr to prevent residual stresses in the glass. Re-annealing is the process of removing objectionable stresses in glass by re-heating it to a suitable temperature, followed by controlled cooling.

annual fuel-utilization efficiency (AFUE): Measures the amount of fuel converted to space heat in proportion to the amount of fuel entering the boiler or furnace, commonly expressed as a percentage. Procedures have been developed by the U.S. Department of Energy to test AFUE.

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

anti-scald: A valve that restricts water flow or fluctuations to help prevent burn injuries. In some areas, plumbing codes require anti-scald valves, so a local professional should be consulted for more information and help with code requirements. See also thermostatic valve.

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

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

antiquated: Obsolete; no longer in use, useful or functioning.

APA plywood: Plywood that has been rated by the American Plywood Association (APA). For example, No. 1 APA-rated exterior plywood contains no voids between its laminate layers.

aperture: The diameter of 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. In commercial applications, equipment other than industrial that is installed or connected as a unit to perform one or more functions.

appraisal: An expert valuation of a property.

approach: The area between the sidewalk and the street that leads to a driveway, or the transitional path from the street leading to the driveway.

approve, approved: Acceptable to the authority having jurisdiction (AHJ); 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 used to resolve complaints, such as InterNACHI's Arbitration Service.

arc-fault circuit interrupter (AFCI): A device intended to provide protection from the effects of arc faults by recognizing characteristics unique to arcing and 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.

architect's rule (or ruler): Three-sided ruler having different scales of measurement 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 the administration of the construction contract.

architectural shingles: Shingles that have added dimensionality because of extra layers or tabs, giving them a shake-like appearance. Also called laminated shingles and three-dimensional shingles.

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

areaway: An open sub-surface space adjacent to a building used to admit light and/or air, or as a means of access to a basement.

asbestos: A common form of magnesium silicate and naturally occurring mineral fiber that was used in various construction products and older homes because of its stability and resistance to fire. Asbestos is also the name given to certain inorganic minerals in their fibrous form. Although asbestos is fire-resistant, it is considered a serious health hazard because its extremely fine fibers are easily inhaled, and exposure to these fibers over a long period of time has been linked to cancers of the lung and the lung-cavity lining, as well as asbestosis, which is a severe lung impairment. Homeowners should be alert for the existence of friable asbestos (that which is readily crumbled or brittle) and always seek professional advice before disturbing 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 or value placed on a property.

associate member: Beginning or probationary level of inspection association membership. See also candidate.

astragal: A molding that 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 drywalled ceiling of a home providing access to the attic.

attic ventilators: In houses, the 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 may also consist of power-driven fans used as an exhaust system.

auger: A tool used by carpenters to bore holes into wood.

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 may be the building owner, health department, building code officer, municipal inspector, building department, or fire marshal.

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

automatic fire-extinguishing system: A system of devices and equipment that automatically detects a fire and discharges water or a fire-retardant medium in an attempt to put the fire out.

automatic sprinkler system: An automated sprinkler system activated for fire-protection purposes.

awning window: A window with hinges at the top that allow it to open out and up.