Home Inspection and
Building Inspection Terms

The following glossary will help you understand home inspection terms:

Select a Letter

• A •

Abatement:  Procedures used to control fiber release of asbestos from asbestos-containing materials, including removal, encapsulation, enclosure and repair.

Amp:  The rate of flow of electricity through conductors.

Apron:  A paved area, such as the juncture of a driveway with the street or garage entrance.

Asbestos-Containing Material (ACM), Asbestos-Containing Building Material (ACBM):  By EPA definition, any material containing more than one percent asbestos by weight.

Asbestos:  Any hydrated mineral silicate separable into commercially usable fibers, including, but not limited to, chrysotile, amosite, crocidolite, tremolite, anthophyllite, and actinolite.

Asphalt:  Most native asphalt is a residue from evaporated petroleum.  Asphalt is insoluble in water but soluble in gasoline and melts when heated.  It is widely used in buildings for waterproofing roof coverings of many types, exterior wall coverings, flooring tile, and the like.

• B •

Batten:  Narrow strips of wood used to cover joints or as decorative vertical members over plywood or wide boards.

Beam:  A structural member transversely supporting a load.

Bearing Wall:  A wall that supports the floor or roof of a building.

Bibb:  A water faucet to which a hose may be attached, also called a hose bibb or sill cock.

Brace:  An inclined piece of framing lumber applied to wall or floor to stiffen the structure.  Often used on walls as temporary bracing until framing has been completed.

BTU:  A BTU, which stands for British Thermal Unit, is a measure of heat.  One BTU is roughly equivalent to that given off by burning one wooden kitchen match.  BTUs are used to measure both heat gain and heat removal.  For example, a 10,000 BTU per hour air conditioner will remove 10,000 BTUs of heat from a room in one hour.  The energy content of oil, gas and electricity can also be measured in BTUs as follows:

• One cubic foot of natural gas contains approximately 1,030 BTUs.
• One gallon of number two heating oil contains approximately 138,000 BTUs.
• One kilowatt-hour of electricity is equal to 3,413 BTUs.

Bulkhead:  Near water, the retaining wall which separates a body of water from land.  In a building, the enclosure for the top of a stairway at the roof level of a building.

Buttress:  A projecting structure, usually masonry or wood, supporting or giving stability to a wall.

• C •

Cantilever:  A structural member which projects beyond its supporting column or wall, and supports a load.

Carpenter Ants:  Ants that bore through wood.  Like termites, carpenter ants like warm, moist areas such as those found in wood structures in this part of the country.  Carpenter ants differ from termites in several important ways.  Carpenter ants do not ingest the wood; rather, they tunnel through the wood leaving a residue of sawdust.  Also differing from termites, carpenter ants can nest anywhere; it is not uncommon to find a carpenter ant nest in an attic.  Carpenter ants can do a great amount of structural damage.  By the time the sawdust residue is visible, structural damage may already have occurred.  Exterminating carpenter ants is difficult.  To exterminate them, one must first find the nest.  Finding the nest is the most difficult part of exterminating carpenter ants.

Caulking:  A flexible putty-like compound used to fill gaps between windows, doors, trim, etc., and the structure they are mounted in.  Caulking helps prevent air and water infiltration.

Cesspool:  An underground catch basin for liquid waste, usually lined with brick, concrete, or stone, capable of drainage into the surrounding soil.

Cockloft:  The air space between the underside of a flat roof and the top floor ceiling.

Column:  In architecture, a perpendicular supporting member, circular or rectangular in section, usually consisting of a base, shaft, and capitals.  In engineering, a vertical structural compression member which supports loads acting in the direction of its longitudinal axis.

Concrete:  A hardened mixture of cement, aggregate and water.  The cement portion is generally portland cement which is made by heating raw materials containing alumina and calcium.  The aggregate is generally sand or gravel.

Condensation:  In a building, beads or droplets of water (and frequently frost in extremely cold weather) that accumulate on the inside of the exterior covering of a building when warm, moisture-laden air from the interior reaches the temperature that no longer permits the air to sustain the moisture it holds.  Use of louvers or ventilators will reduce moisture condensation in attics.  A vapor barrier under the gypsum lath or dry wall on exposed walls will reduce condensation in them.

Conduit, Electrical:  A pipe, usually metal, in which one or more wires are installed.

Conduit, Non-Electrical:  Any small passage or channel that goes from one area to another.

Copalum Connector:  A special type of crimp connector the US Consumer Product Safety Commission recommends when pigtailing Copper wires to Aluminum wiring.

Cornice:  A horizontal piece, usually molding, that tops a column, wall, etc.

Crawl Space:  A shallow space, usually below the living quarters of a building that has no basement, normally enclosed by the foundation wall.  Other shallow spaces throughout a building may also be called crawl spaces.

• D •

Dormer:  An opening in a sloping roof, the framing of which projects out to form a vertical wall suitable for windows or other openings.

• E •

Eaves:  The lower part of a roof projecting over the wall.

Electric Heat:  Electric Heat was popular for a short time when electricity costs were low.  Now, electric heat is seldom used in new construction.  Electric heat has the advantage of allowing you to adjust room temperatures individually.  Unfortunately, electric heat is expensive to operate. For that reason, many people keep the temperature low, particularly in rooms they seldom use.

Expansion Tank:  Part of a hot water heating system that is filled with air. Its purpose is to provide a cushion for the expansion of the hot water in the heating system.  (Many people confuse expansion tanks with hot water storage tanks.)

• F •

Fascia:  A flat board, band, or face, usually used in combination with moldings, and often located at the outer face of the cornice.

Flagstone, Flagging, Flags:  Flat stones, from one to four inches thick, used for rustic walks, steps, floors, and the like.

Flashing:  Sheet metal or other material used in roof, window, door, and wall construction to protect a building from water seepage.

Flue:  The space or passage in a chimney through which smoke, gas, or fumes ascend.  Each passage is called a flue, which together with any other flues and the surrounding masonry make up the chimney.

Footing:  A masonry section, usually concrete, usually rectangular and wider than the bottom of the foundation wall or pier it supports.

Forced Hot Air Heating:  Heating system where a fan circulates air over a heat exchanger in a furnace, and back through the building to heat the building.  Forced hot air heating systems are used in many buildings today.  Contrary to popular belief, forced hot air heating ducts are not well suited to conversion to central air conditioning.  This is because forced hot air ducts are at floor level, while air conditioning ducts should be at ceiling level for optimum cooling.  Most forced hot air systems have filters that need to be changed frequently.

Foundation:  The supporting portion of a structure at the bottom of the structure.  The foundation supports the building.

Furnace:  Strictly speaking, an enclosed area for heating air.  In common usage, a furnace is taken to mean any piece of equipment where fossil fuel is converted to heat.

Furring:  Strips of wood or metal applied to a wall or other surface to make the surface even.  Furring normally serves as a fastening base for finish material.

• G •

Ground Fault Circuit Interrupter (GFCI):  Ground Fault Circuit Interrupters, or GFCIs, are safety devices now routinely installed where electrical outlets and appliances are used in close proximity to water, (and are now required in those areas by the electrical code).  GFCIs sense the current flowing into the conductors of the outlet.  If there is a small imbalance (such as would occur were someone getting an electric shock) the power is rapidly turned off.  This makes the operation of kitchen and bathroom electrical appliances safer.  GFCIs occasionally trip for other reasons, such as a small amount of water being splashed on the outlet.

Girder:  A large beam of wood or steel used to support concentrated loads, (such as joists), at isolated points along its length.

Grout:  Mortar made of such consistency (by adding water) that it will just flow into the joints and cavities of the masonry work and fill them solid.

Ground, Electrical:  Part of the electrical system having zero voltage, electrically connected to the earth.

Gutter:  A gutter is a shallow channel or conduit of metal, wood, or vinyl set along the eaves of a building to catch and carry off rainwater from the roof, and away from the building.

• H •

Header:  A beam over a door, window, or other opening.

Hot Water Booster Tank:  A hot water heater or storage tank used with a tankless hot water heater to increase the reserve capacity.  Alone, hot water booster tanks usually cannot provide sufficient hot water.

Hot Water Heater:  Any device for producing hot water.  Most common are tankless coils used in conjunction with a furnace, or an oil, gas, or electric heater combined with a storage tank.  Most non-commercial hot water heaters are of limited capacity; that is, they are not designed for continuous or heavy use.

Hot Water Heating, Hydronic Heating:  Heating system where water is heated in a boiler, then circulated through radiators to heat a building.  Hot water heating systems are used in many modern one and two-family residences.  In older buildings, the radiators become blocked by dust, and heating efficiency is reduced.  Radiators need to be vacuumed every several years.  Some older systems have no circulator and use convection (the tendency of heated water to rise) to circulate the water in a building.  These are called convection hot water or gravity hot water systems.  Convection hot water heating is inefficient and considered obsolete.  Many people with convection hot water heating choose to convert to circulating hot water when feasible.

Humidifier:  A device designed to increase the humidity within a room or a building by means of the discharge of water vapor.  Humidifiers may consist of individual room size units or larger units attached to a forced hot air furnace to condition the entire building.  Some humidification will make a building seem more comfortable during the dry winter months.  In fact, a room usually feels warmer if the humidity level is higher.  However, too much humidification will cause moisture to build up in the walls and ceilings, and result in possible rot.

Hydronic Heating:  See Hot Water Heating.

• I •

I-Beam:  A steel beam with a cross section resembling the letter I.  An I-beam is used for long spans as basement beams or over wide wall openings, such as above a double garage door that supports wall and roof loads.

• J • K •

Joist:  One of a series of parallel beams, usually one-and-one-half to three inches in thickness, used to support ceiling and floor loads, and supported in turn by larger beams, girders, or bearing walls.

Joist Ribbon:  The wooden member running perpendicular to the joists over the foundation.

• L •

Lally Column:  A steel tubular column usually filled with concrete.

Leader:  A pipe running from a gutter to the ground.

Light, Lite:  Space in a window sash for a single pane of glass.  Also, a pane of glass.

Lintel:  A horizontal structural member that supports the load over an opening such as a door or window, usually used in brick structures.

Lite:  See Light.

Locust Post:  The trunk of a locust tree used as a column.

• M • N •

Masonry:  Stone, brick, concrete, hollow-tile concrete-block, gypsum-block, or other similar building units or materials or a combination of the same, bonded together with mortar to form a wall, pier, buttress, or similar mass.

Moisture Barrier:  Treated paper or metal that retards or bars water vapor, used to keep moisture from passing into walls, floors, and ceilings.  Also used between damp and dry areas, such as between living space and a crawl space.

• O •

Over-Current Device:  Usually a fuse or circuit breaker, a device that limits the maximum amount of current that can flow in a circuit.

• P • Q •

Parapet:  The part of a wall that extends above the roof line.

Partition:  A wall that sub-divides spaces within any story of a building.

Pier:  A column of masonry or other structural material, usually rectangular in horizontal cross section, used to support other structural members.

Pitch:  The incline slope of a roof or the ratio of the total rise to the total width of a building, i.e., an eight-foot rise and 24-foot run is a one-third pitch roof.  Roof slope is expressed in the feet of rise per foot of run.

Plate:  A horizontal member anchored to a masonry wall.

Plumb:  Exactly perpendicular, vertical.

Pointing:  Treatment of joints in masonry by filling with mortar to improve appearance and/or protect against weather.

Powder Post Beetle:  Beetles that lay their eggs in wood.  The holes in the wood are the exit holes where the beetle's offspring exits.  Powder post beetle damage is usually found in structural wood in older structures.  If a significant amount of wood is damaged, it can affect structural soundness.

• R •

Rafter:  One of a series of structural members of a roof designed to support roof loads. The rafters of a flat roof are sometimes called roof joists.

Retaining Wall:  A wall used to hold back earth.

Roof Sheathing:  The boards or sheet material fastened to the roof rafters on which the shingle or other roof covering is laid.

Rot:  Rot is a fungal growth that consumes the cellulose in timber and leaves behind a skeleton that is easily reduced to powder or comes apart in cube-shaped chunks.  Rot occurs in damp and moist areas.  When rot becomes apparent, it is often the tip of the iceberg.  Rot is often not visible until it becomes a serious problem.  Rot frequently appears suddenly.  It is not that rot spreads so rapidly, although rot can spread rapidly; rather, sound wood often obscures rotted wood.  It is therefore important to frequently check any wood that is exposed to moisture for rot.  Raised decks, porches, wood handrails, and other exterior improvements are hazardous when they rot and should be checked frequently.

• S •

Saddle:  Two sloping surfaces meeting in a horizontal ridge, used between the back side of a chimney, or other vertical surface, and a sloping roof.

Sash:  A single light frame containing one or more lights of glass.

Screw Jack:  An adjustable steel column.

Septic Tank:  A sewage settling tank in which part of the sewage is converted into gas and sludge before the remaining waste is discharged by gravity into a leaching bed underground.  Septic tanks should be pumped at least every three years.

Shake:  A thick hand split shingle, re-sawed to form two shakes; usually edge grained.

Sheathing:  The first covering of boards or other material on the outside wall or roof prior to installing the finished siding or roof covering.

Shingle, Roof:  Covering of asphalt, asbestos, wood, tile, slate or other material cut to stock lengths, widths, and thickness.

Shingle, Siding:  Various kinds of shingles, such as wood shingles or shakes and non-wood shingles, that are used over sheathing for exterior sidewall covering of a structure.

Shutter:  Usually lightweight louvered or flush door-like frames located at each side of a window.  Some shutters are made to close over the window for protection; most are fastened to the wall as a decorative device.

Siding:  The siding is the finish covering of the outside wall of a frame building.  It is usually made of horizontal weatherboards, vertical boards with battens, shingles, brick, stone, asbestos shingle, shakes, or other weather resistant material.  Siding is like a protective skin.  As long as siding performs this function, it is acceptable no matter how worn.

Sill:  The lowest member of the frame of a structure, resting on the foundation and supporting the floor joists or the uprights of the wall (also sill plate or mud sill).  Also, the member forming the lower side of an opening, as a door sill, window sill, etc.

Sister Joist:  An additional joists installed next to an existing joist for purposes of additional strength.

Soffit:  Usually the underside of an overhanging cornice.

Sole Plate:  Bottom horizontal member of a frame wall.

Spalling:  Condition of concrete when small pieces are breaking off due to wear, use of salt, or other reasons.

Span:  The distance between structural supports such as walls, columns, piers, beams, girders, and trusses.

Steam Heat:  One of the first types of central heating systems, still found in many private residences and buildings today.  Steam heating systems were used until the 1950s, and even later in large buildings.  Steam heat offered many advantages in the early part of the century when central heat became popular:  Steam heating systems were simple to install in existing buildings.  There were few moving parts.  Steam could easily heat large buildings that could not be practically heated by any other system of the day.  By today’s standards, steam heat is noisy and inefficient.  There is also a long delay between the time the thermostat calls for heat to the time heat becomes available.  Once the radiators warm up, they continue to radiate heat after the boiler has shut off.

Stucco:  Most commonly refers to an outside plaster made with Portland cement as its base.  Stucco is subject to developing cracks, which should be patched as soon as they occur to prevent water penetration.

Stud:  One of a series of slender wood or metal vertical structural members placed as supporting elements in walls and partitions.

Sub-Floor:  Boards or plywood laid on joists over which a finish floor is to be laid.

Swale:  A wide shallow depression in the ground which forms a channel for storm drainage.

• T • U •

Termite Shield:  A shield, usually of non-corrodible metal, placed in or on a foundation wall or other mass of masonry or around pipes to help prevent the passage of termites.

Termites:  Insects that superficially resemble ants in general appearance, and live in colonies; termites are frequently called white ants.  Subterranean termites establish themselves in buildings not by being carried in with lumber, but by entering from ground nests after the building has been constructed.  If unmolested, termites eat out the wood, leaving a shell of sound wood to conceal their activities.  Damage may proceed so far as to cause collapse of parts of a structure before discovery.  There are about 56 species of termites known in the United States; but the two major ones, classified by the manner in which they attack wood, are ground inhabiting or subterranean termites (the most common and found here in the Northeast) and dry wood termites which are found almost exclusively in the South.

Termites are primitive insects belonging to the order Isopteran.  They are closely related to cockroaches.  They are different from almost all other insects in that they can convert the cellulose of wood back into sugar and utilize it.  Termites are able to do this because of single-cell organisms harbored in their digestive tracts which convert cellulose into simple substances which the termites can digest.  In nature termites helped convert dead wood and other materials containing cellulose into humus.  When man began building structures of wood termites started to feed on man's structures.

The subterranean termites of the Northeastern states are native soil inhabiting insects which feed on wood, paper, and similar cellulose materials.  In forests, termites are beneficial in that they help to decompose fallen trees and stumps and return the wood substances to the soil to be used again by other trees.  The economic importance of termite attacks on buildings arises from the fact that the wood members of a building closest to the soil, and therefore the most likely to be severely damaged by the termites, are usually sills, joists, studs, girders and other important load bearing elements of construction.

Failure to stop termite attack can result in loss of support so that other forms of building deterioration, such as sagging walls and leaking surfaces can follow.  Heated buildings whose construction places wood in direct contact with or in close proximity to the soil thus offer termites the ideal environment: a favorable year round climate and an abundant sheltered food source.  Sometimes buildings where wood is placed in close contact with the soil, but without heat in the winter, (such as barns), stand for decades with no termite attack of any consequence.  When such buildings are remodeled into residences, etc., and supplied with heat, serious termites damage often follows in a few years.

Ton:  The size of an air conditioner or heat pump is sometimes expressed in tons.  The term dates from the days when ice, measured in tons, was used to cool large buildings.  A ton is equal to 12,000 BTUs per hour.  A 12,000 BTU per hour air conditioning unit is often referred to as a one-ton air conditioner; an 18,000 BTU per hour unit as a one-and-one-half-ton unit, etc.

Tongue and Groove:  Boards or planks machined in such a manner that there is a groove on one edge and a corresponding tongue on the other.

Top Plate:  Top horizontal member of a frame wall supporting ceiling joists, rafters, or other members.

Trap:  A bend in a water pipe to hold water so gases will not escape from the plumbing system into the building.

Trim:  The finish materials in a building, such as moldings applied around openings (window trim, door trim) or at the floor and ceiling of rooms (baseboard, cornice, and other moldings).  Trim is usually not structural, but serves to keep moisture from penetrating into a building.

Truss:  A frame or jointed structure designed to act as a beam of long span, which each member is usually subjected to longitudinal stress only, either tension or compression.  Trusses are used to reduce the amount of wood needed in a structure, and hence the cost of a building.  Although a truss may look flimsy, a properly designed and built truss can carry a load as well as the more common joists and rafters.

• V •

Valley, Valle:  The internal angle formed by the junction of two sloping sides of a roof.

Vapor Barrier:  Material used to retard the movement of water vapor into walls and prevent condensation in them.  A vapor barrier is applied separately over the warm side of exposed walls or as a part of batt or blanket insulation.

Volt:  A unit of measure of electrical potential.

• W • X • Y • Z •

Watt:  A unit of power equal to the volts applied times the current flowing (measured in amps). One kilowatt is 1000 watts.  A kilowatt-hour is the product of watts times the time (measured in hours).  It is watts, not volts or amps, that determines if a building has sufficient power.

Weather-Strip:  Narrow or jamb width sections of thin metal or other material to prevent infiltration of air and moisture around windows and doors.  Compression weather stripping prevents air infiltration, provides tension, and acts as a counter balance.