National Home Inspector Examination key terms

The widened concrete base at the bottom of a foundation wall, pier, or column. It spreads the weight of the building over a larger area of soil so the soil is not overloaded.

The vertical concrete or masonry wall that carries loads from the house above down to the footing and holds back soil around a basement or crawlspace.

A wall that carries weight from floors or the roof above down to the foundation. Removing or cutting into it without adding support can cause sagging or collapse.

A horizontal framing member that supports a floor and the loads placed on it. Joists span between beams or walls and are commonly spaced 16 or 24 inches apart.

A heating appliance that burns gas, oil, or propane in a heat exchanger and blows warmed air through ducts to heat the house.

A device that moves heat instead of creating it, taking heat from outdoor air to warm the house and reversing the process to cool it.

The indoor cabinet that contains the blower, heating or cooling coil, and filter, and moves conditioned air through the duct system.

A small pipe that carries water collected by an air-conditioning coil or high-efficiency furnace to a floor drain, sump, or condensate pump.

The overhead or underground wires and associated equipment that bring utility power from the pole or transformer to the home's main panel.

The metal enclosure holding the main disconnect, circuit breakers, and bus bars, where incoming power is divided into branch circuits for the house.

Ground-fault circuit interrupter. A device that cuts power almost instantly when current leaks to ground, protecting people in wet locations such as kitchens, baths, and exteriors.

Arc-fault circuit interrupter. A breaker or receptacle that shuts off power when it senses the electrical signature of a dangerous arc in wiring.

A rod, pipe, or plate driven into the earth and connected to the electrical system, giving stray current and surges a safe path to ground.

A U-shaped section of pipe under a fixture that holds a small amount of water, blocking sewer gases from rising into the building.

Temperature and pressure relief valve. A safety valve on a water heater that opens to release excess heat or pressure before the tank can rupture.

A valve or assembly that stops water from reversing direction in the piping, keeping contaminated water from entering the potable water supply.

Drain-waste-vent system. The network of pipes that carries wastewater away, admits air for smooth flow, and vents sewer gas to the outdoors.

The valve, usually located where the water service pipe enters the house, that stops all water flow to the building for repairs or emergencies.

Sheet metal or another water-resistant material installed at roof joints and penetrations to direct water away from places where it could leak into the structure.

Small L-shaped pieces of metal installed one per shingle course where a roof meets a wall, keeping water from getting behind the siding.

A metal lip along the roof edges that makes water drip clear of the fascia and decking instead of wicking back under the shingles.

The V-shaped intersection where two roof slopes meet. It concentrates runoff, so it needs extra underlayment and carefully installed flashing.

A water-resistant layer of felt or synthetic sheet laid over the roof decking beneath the shingles, acting as a secondary barrier against moisture.

The slope of the ground surface. Finish grade should fall away from the house so surface water drains off rather than pooling against the foundation.

The depth to which soil freezes in winter. In cold climates, footings must extend below this depth so frost heaving does not lift the structure.

The board fastened to the house that supports one end of the deck joists. It must be properly flashed and attached or moisture and loads can cause failure.

Panels of gypsum board faced with paper, used as interior wall and ceiling finish. Joints and fasteners are taped and covered with compound.

An operable window with enough clear opening and a low enough sill for a person to escape through in a fire, required in sleeping rooms by most codes.

The vertical face of a step between one tread and the next. Uneven riser heights are a common trip hazard and a frequent inspection finding.

The wall and ceiling assembly between an attached garage and the living space, built to resist fire for a rated period and usually fitted with a self-closing door.

A measure of how well a material resists the flow of heat. Higher numbers mean better insulating performance and depend on material type and thickness.

A material that slows the movement of water vapor through walls and ceilings. In cold climates it is typically placed on the warm side of the insulation.

An opening in the underside of a roof overhang that lets outside air into the attic, working with vents higher on the roof to keep the space dry.

Closing gaps and cracks in the building envelope, such as around pipes, wires, and framing, so air does not leak in or out and waste energy.

A published set of minimum requirements describing which systems and components an inspector must examine and what the inspection is not required to cover.

A problem with a system or component that significantly affects value or poses an unreasonable risk to people, and that the client may not have been aware of.

A written contract signed before the inspection that explains the scope, limitations, fees, and the standards of practice the inspector will follow.