64 terms
Home inspection glossary
Plain-language definitions of terms that come up in home inspection study and practice.
3 4 A B C D E F G H I K L N O P R S T V W
- 3-2-10 rule
- A chimney extends 3 ft above the roof and 2 ft above anything within 10 ft.
- 4-inch sphere rule
- Guard openings must not let a 4-in. sphere pass through.
- AFCI
- Arc-fault circuit interrupter. A breaker or device that trips on dangerous arcing to reduce fire risk.
- Air admittance valve (AAV)
- A one-way vent valve that lets air into a drain system without a roof vent where allowed.
- Anode rod
- A sacrificial metal rod in a tank water heater that corrodes so the tank doesn't.
- Backdrafting
- Combustion gases flowing back into the house instead of up the vent.
- Baffle (attic)
- A chute that keeps insulation away from the soffit vents so intake air can flow.
- Bonding
- Connecting metal parts so they stay at the same electrical potential.
- Counterflashing
- Flashing set into a wall or chimney that laps over the base or step flashing.
- Creosote
- A combustible tar-like deposit from wood smoke that builds up in flues.
- Cricket (saddle)
- A small roof structure behind a chimney that diverts water.
- CSST
- Corrugated stainless steel tubing for gas, which needs bonding per the manufacturer.
- Dielectric union
- A fitting that separates dissimilar metals to prevent galvanic corrosion.
- Double tap
- Two conductors under a breaker terminal made for one.
- Drip edge
- Metal at the roof edges that directs water into the gutter.
- Drip leg (sediment trap)
- A capped pipe tee before a gas appliance that catches debris.
- Efflorescence
- White mineral salts left on masonry by water passing through it.
- Egress opening
- A window or door that allows emergency escape from a sleeping room or basement.
- EIFS
- Exterior insulation and finish system, a synthetic stucco.
- Expansion tank
- A tank with an air cushion that absorbs thermal expansion in closed water systems.
- Flue
- The passage in a chimney or vent that carries combustion gases outdoors.
- GFCI
- Ground-fault circuit interrupter. Trips when current leaks to ground, protecting people from shock.
- Girder
- A main beam that supports floor joists.
- Grounding electrode conductor
- The wire connecting the service to the ground rod or other electrodes.
- Hearth extension
- A noncombustible floor area in front of and beside a fireplace opening.
- Heat exchanger
- The furnace part that separates combustion gases from the house air.
- I-joist
- An engineered joist with flanges and a web. Don't cut the flanges.
- Ice dam
- A ridge of ice at the eaves that backs up meltwater under the roofing.
- Kick-out flashing
- Flashing at the bottom of a roof-wall joint that diverts water into the gutter.
- Knob-and-tube
- Early ungrounded wiring on ceramic knobs and tubes.
- Ledger
- A board fastened to the house that supports deck joists.
- Lintel
- A beam over a masonry opening.
- Low-water cutoff
- A boiler control that shuts the burner off when the water is low.
- Negative grade
- Ground sloping toward the foundation.
- Overfusing
- A breaker or fuse rated higher than the wire can safely carry.
- P-trap
- A U-shaped drain trap that holds water to block sewer gas.
- PEX
- Cross-linked polyethylene supply tubing. Protect it from UV light.
- Polybutylene
- Gray plastic supply pipe with a history of failures.
- Pre-inspection agreement
- A written contract setting scope, fee and limits before the inspection.
- R-value
- Resistance to heat flow. Higher is better.
- Rafter thrust
- The outward push of rafters on walls when there are no ties.
- Relief valve (TPR)
- A temperature and pressure relief valve that opens to prevent tank explosions.
- Reversed polarity
- Hot and neutral swapped at a receptacle.
- Rim joist
- The joist around the perimeter of the floor framing.
- Safety glazing
- Tempered or laminated glass required in hazardous locations.
- Service drop
- Overhead utility conductors to the house.
- Service lateral
- Underground utility conductors to the house.
- Sill plate
- Lumber anchored to the top of the foundation.
- Sistering
- Fastening a new member alongside a damaged joist or rafter.
- Soffit
- The underside of a roof overhang, often vented.
- Spalling
- Flaking or breaking off of a concrete or masonry surface.
- Standards of practice (SOP)
- The minimum scope and exclusions for a home inspection.
- Step flashing
- L-shaped flashing pieces woven with shingles along a sidewall.
- Subpanel
- A panel fed from the main service, with neutrals and grounds kept separate.
- Sump pump
- A pump that removes groundwater from a pit and discharges it away from the house.
- Swale
- A shallow channel that directs surface water.
- Temperature split
- The difference in air temperature across a cooling coil.
- Truss
- An engineered roof or floor framework. Never alter its members.
- Valley
- The internal angle where two roof slopes meet.
- Vapor retarder
- Material that slows water vapor diffusion.
- Vent connector
- The pipe between an appliance and its chimney or vent.
- Weep holes
- Openings at the base of brick veneer or walls that let water out.
- Weep screed
- A metal strip at the base of stucco that lets water drain out.
- Window well
- An excavated area around a below-grade window. Needs drainage, and a ladder if deep.