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Below are terms related to homes and their systems and components. You may encounter these terms in your Home Inspection Report or when communicating with other inspectors or contractors about your home.

V - Z

vacuum breaker: An anti-siphon device that prevents wastewater from being drawn back into supply lines and potentially contaminating the water supply; a type of backflow preventer.


valley: The internal angle formed by the junction of two sloping sides of a roof.


valley flashing: Sheet metal or other material used to line a valley in a roof to direct rainwater down into the gutter system.


valley rafter: A rafter of double 2-inch-thick members that forms the intersection of an internal roof angle.


valley shield: A quality underlayment installed for added protection in the areas of a roof that experience heavy water flow. This self-adhering product has a waterproof asphalt coating that offers excellent elongation and recovery properties for accommodating roof expansion and contraction and structural movement.


valve: A device to stop, start or regulate the flow of liquid or gas through or from piping.


vapor: The gaseous form of a substance.


vapor barrier: A a plastic or foil membrane that is placed between the insulation and the roof deck, as well as the ceiling, wall and floor assemblies, which resists the diffusion of water vapor from the building and into the insulation, where it may subsequently condense into liquid water and cause structural problems.


vapor diffusion retarder (vapor retarder): Any substance, including a treated paper or foil membrane, special paint or film that prevents the transmission of water vapor. Vapor diffusion retarders are effective for controlling moisture in basements, crawlspaces, and slab-on-grade foundations.


varnish: A thickened preparation of drying oil, with or without resin, that is suitable for spreading on surfaces to form a continuous, transparent coating, or for mixing with pigments to make enamels.


vehicle: The liquid portion of a finishing material that consists of the non-volatile binder and volatile thinners.


veining: In roofing, the characteristic lines that develop during the aging process of soft bitumens. Also, minor cracking that resembles spider veins occurs naturally during the curing process of cement. These cracks are normal and no cause for alarm, unless they grow, which would indicate a potential problem requiring further investigation.


veneer: A thin surface layer of wood or decorative brick facing that is overlaid and adhered as a façade to a base of inferior materials.


vent: A pipe or duct that permits the flow of air as an inlet or outlet; to create a vent or system of venting.


vent pipe: A vertical pipe of relatively small dimensions that protrudes through a roof to provide for the ventilation of gases or exhaust from various combustion systems or appliances, including a heater/furnace, clothes dryer, water heater, etc., as well as stale or damp air, odors, grease and contaminants, such as from a range, bathroom, attic, etc.


vent stack: A vertical vent pipe installed for the purpose of providing circulation of air to and from any part of a drainage system.


vent system: In plumbing, a system that provides air flow to or from a drain-waste-vent (DWV) system, or the circulation of air within such a system to protect traps and seals from siphonage and back-pressure.


ventilation: The natural or mechanical process of exchanging air in an interior space, and includes both the exchange of air to the outside, as well as the circulation of air within a building. It is one of the most important factors for controlling excessive moisture indoors and for maintaining acceptable indoor air quality.


ventilator: A device installed on a roof for the purpose of ventilating the interior of the building.


venting: The process of installing roof vents in a roof assembly to relieve vapor pressure. Also, the process by which water in the insulation course of the roof assembly evaporates and exits via the roof vents. See also vent and ventilation.


vermiculite: An aggregate similar to perlite that is formed from mica, a hydrous silicate, with the ability to expand upon heating to form a lightweight material with insulative qualities. Used in lightweight roof decks and deck infills, as well as bulk insulation, and as aggregate in acoustical plaster and concrete.


viscosity: The extent to which a fluid resists a tendency to flow.


visible light transmittance: The percentage of visible light within the solar spectrum (390 to 770 nanometers) that is transmitted through glass.


Visqueen: The brand name for a U.K.-based product of 4-mil to 10-mil plastic sheeting used as a groundcover and vapor barrier in the crawlspace of a home, a damp-proof course in a roof, a damp-proof membrane for exterior walls, a protective tarpaulin over setting concrete, and a waterproof membrane to line decorative ponds.


vitreous China: A non-porous ceramic that is coated with a ceramic glaze to form toilets and lavatories.


void: A rectangular cardboard box that is installed between the earth (between caissons) and a concrete foundation wall in the presence of expansive soils.


volatile thinner: A liquid that evaporates readily and is used to thin or reduce the consistency of finishes without altering the relative volumes of pigment and non-volatile vehicles.


voltage: The driving force behind the flow of electricity, similar to the pressure in a water pipe. Most U.S. homes are wired with 110- and 220-volt lines, with the 110-volt power used for lighting and most of the other circuits, and the 220-volt power used for the refrigerator/freezer, stove, water heater, clothes washing machine and dryer, and similar large household appliances.


voltmeter: A device that measures the voltage flowing through a circuit.



waferboard: Another name for particleboard.


walkway: An exterior area designated for foot traffic.


wall protector: A non-combustible shield between a wall and anything heat-producing for the purpose of reducing required clearance.


wall-out: To spray-paint the interior of a home.


wane: The defective edge of a wood board caused by remaining bark or a beveled end.


warping: Any distortion in a material.


waste and overflow: A bathtub drain assembly that has an outlet near or at the top to remove overflow water when filling the tub and an outlet at the bottom to remove wastewater when the tub is drained.


waste pipe and vent: Plastic plumbing pipe that carries wastewater to the municipal sewage system.


water board: Drywall with an outer layer of water-resistant paper, typically green or blue, that is used in tub and shower locations. Also called greenboard.


water closet: Another term for toilet.


water meter pit: The box, cast-iron bonnet and concrete rings that contain the water meter. Also called a water meter vault.


water table: The location of naturally occurring underground water, and the vertical distance from the surface of the earth to this underground water. Water tables vary by locality, geography, etc.


water tap: The point at which the home water line connects to the main municipal water system.


water vapor: Moisture in its gas state in air.


water-cement ratio: The ratio of cement to water in a concrete mixture, which ultimately determines the concrete's strength. More water in the mix results in a weaker concrete. Concrete mixes are identified in ratios of cement to fine aggregate to coarse aggregate. For example, the ratio 1:2:4 refers to a mix consisting of 1 cubic foot of cement, 2 cubic feet of sand, and 4 cubic feet of gravel. Cement and water are the two chemically active elements in concrete which, when combined, form a paste or glue that coats and surrounds the particles of aggregate and, upon hardening, binds the entire mass together.


water-repellent coating: A transparent coating or sealer applied to the surface of concrete and masonry surfaces to repel water.


water-repellent preservative: A liquid designed to penetrate into wood to repel water and provide a moderate level of protection. It is used for millwork, such as sashes and frames, and is usually applied by dipping.


waterproof, waterproofing: Descriptive of a product and the process by which a building component is made totally resistant to the passage or penetration of water and/or water vapor.


wattage: The electrical unit of power. A kilowatt equals 1,000 watts. Customers of an electric utility are billed on a monthly basis according to the number kilowatts of power they have used (or are predicted to use under budget billing plans).


wax ring: A thick, pre-formed wax ring located between a toilet's bowl and the floor flange, which provides a watertight connection to the soil drain (sewer).


WC: Abbreviation for water closet (toilet).


weatherization: The work on a building's exterior features with the goal of reducing its energy consumption (heating and/or cooling), and typically involving adding insulation, installing storm windows and doors, caulking cracks, and adding weatherstripping.

weatherstrip, weatherstripping: Jamb-width or narrower sections of thin metal, rubber or other material that prevent the infiltration of air and moisture around windows and doors. Compression weatherstripping prevents air infiltration, provides tension, and acts as a counter-balance.


weathertight: Sealed against the intrusion of rain, snow, cold air, etc.


weep hole: A hole located near the base of a masonry or glazing structure that allows for the drainage of entrapped water.


weep screed: A type of flashing material installed along the base and at roof-wall transitions of exterior stucco or stone that drains excess moisture.


weld: The joining of components by fusing; also, the resulting joint. To join (metals) by applying heat with pressure or an intermediate or filler metal having a high melting point. In thermoplastics, refers to the bonding together of a membrane using heat or solvents.


well casing: A steel or plastic pipe that serves as the lining of a well, preventing it from caving in, and protecting groundwater from contamination by surface water.


well casing head: A heavy, flanged steel fitting connected to the first string of a casing.


well house: A structure that encloses a private well.


wet or dry surface plastic roof cement: A general-purpose exterior repair and maintenance material that can be used on both damp and dry surfaces, and typically used to stop roof leaks.


wet seal: An elastomeric sealant between window glass and its sash to form a weathertight seal.


whole-house fan: A type of fan or exhaust system installed in a home's attic that is designed to pull air out of the building and force it into the attic space, causing a positive pressure differential in the attic, and forcing the air out through the gable or soffit vents, while simultaneously producing a negative pressure differential inside the living areas, which draws air in through open windows; not to be confused with an attic fan, which removes some hot air from the attic space.


widespread: In plumbing, a style of lavatory faucet whose spout and handles are separate. Flex hoses are used between the spout and handles to allow adjustable centers.


wind bracing: Metal straps or wood blocks installed diagonally on the inside of a wall from bottom to top plate that prevent the wall from twisting, racking or falling over in a domino fashion.


wind uplift: The upward force exerted by wind traveling across a roof.


window: An opening constructed in a wall or roof that functions to admit light or air to an enclosure and is typically framed and spanned with glass mounted to permit opening and closing; a framework enclosing a pane of glass for such an opening; a sash; a pane of glass or similar material enclosed in such a framework.


window buck: A square or rectangular box (buck) that is installed within a concrete foundation or block wall for a window that will eventually be installed during the siding stage of construction.


window frame: The stationary part of a window unit; the window sash fits into the window frame.


window sash: The operating or movable part of a window; the sash is made of window panes and their borders.


wire nut: A plastic cap used to cover and connect bare wires together.


wire size: A system used to determine the resistance of electrical wire. Conductors for building wiring are available in AWG (American Wire Gauge) sizes ranging from No. 14 to 4/0. The larger the number size, the smaller the diameter. For example, 10 wire is smaller than 8. The larger the diameter of a wire, the less its resistance.


WonderBoard®: A panel made of concrete and fiberglass used as a ceramic-tile backing material, typically on bathtub decks.


wood filler: A heavily pigmented preparation used for fining and leveling off the pores in open-pored woods.


wood-fiber plaster: A plaster consisting of calcified gypsum that is integrally mixed with selected coarse cellulose to provide bulk and coverage. It is formulated to produce high-strength base coats for use in highly fire-resistant ceiling assemblies.


work life: The time during which a curing sealant remains suitable for use after being mixed with a catalyst.


woven valley: A method of valley construction by which shingles from both sides of the valley extend across the valley and are woven together by overlapping alternate courses as they are applied. The valley flashing is not exposed.


wrapped drywall: Areas that get complete drywall covering, as in the doorway openings of bifold and bypass closet doors.


wythe: A wythe is a continuous vertical section of masonry one unit in thickness. A wythe may be independent of, or interlocked with, the adjoining wythe(s). A single wythe of brick that is not structural in nature is referred to as a veneer. A multiple-wythe masonry wall may be composed of a single type of masonry unit layered to increase its thickness and structural strength, or different masonry units chosen by function, such as an economical concrete block serving a structural purpose and a more expensive brick chosen for its appearance.



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Y (wye): A Y-shaped plumbing fitting used to attach branch lines or to redirect flow.


yard: An open space on the same lot with a building.


yard of concrete: One cubic yard of concrete that is 3x3x3-feet in volume, or 27 cubic feet. One cubic yard of concrete will pour 80 square feet of a sidewalk or basement or garage floor that is 3-1/2 inches thick.


yoke: The location of a home's water meter installed in a pit in the yard between two copper pipes.



Z-bar flashing: Bent, galvanized metal flashing that is installed above a horizontal trim board of an exterior window, door, or brick run that prevents water from getting behind the trim/brick and into the home.


zone: The section of a building that is served by one heating or cooling loop because it has noticeably distinct heating or cooling needs. Also, the section of property that is watered by a lawn sprinkler system.


zone valve: A device placed near the heater or cooler that controls the flow of water or steam to parts of a building and controlled by a zone thermostat.


zoning: A governmental process and specification that limits the use of a property, such as for single-family use, high-rise residential use, commercial use, industrial use, etc. Zoning laws typically limit where a particular structure can be built and are related to the locality's building codes.

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