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Term Definition
Foundation

Component that transfers weight of building and occupants to the earth.

Framed Connections

Connections joining structural steel members with a metal, such as an angle, that is secured to the web of the beam.

Framing Plan

A drawing showing the location of structural members.

Freezing Cycle Day

A day when the temperature of the air rises above or falls below 32 degrees Fahrenheit or 0 degrees Celcius.

Freezing Point

The temperature at which a given substance will solidify (freeze).

Frequency (Sound)

Number of complete vibrations or cycles or periodic motion per unit of time.

Front Yard

In zoning, the minimum legal distance between the front property line and a structure.

Frontage

The length of a lot line along a street or other public way.

Frost Line

The maximum depth in the earth to which the soil can be expected to freeze during a severe winter.

Frost Line

The deepest penetration of frost below grade.

Frost Point

The temperature at which frost forms on exposed, chilled surfaces.

Fuel Contributed

A rating of the amount of combustible material in a coating.

Furring

Member or means of supporting a finished surfacing material away from the structural wall or framing. Used to level uneven or damaged surfaces or to provide space between substrates. Also an element for mechanical or adhesive attachment of paneling.

Fuse

An overcurrent protection device that opens an electric circuit when the fusible element is broken by heat due to overcurrent passing through it.

Fusion-Bonded Construction

Carpet formed by bonding pile yearn between two sheets of backing material and cutting the pile yarn in the center, forming two pieces of carpet.

Gable

Uppermost portion of the end wall of a building that comes to a triangular point under a sloping roof.

Galling

The wearing or abrading of one material against another under extreme pressure.

Galvanic Corrosion

Corrosion that develops by galvanic action when two dissimilar metals are in contact in the atmosphere.

Gearless Traction Elevator

An elevator with the traction sheave connected to a spur gear that is driven by a worm gear connected to the shaft of the electric motor.

Girder

Beam, especially a long, heavy one; the main beam supporting floor joists or other smaller beams.

Glass

An inorganic mixture that has been fused at a high temperature and cooled without crystallization.

Glazed Structural Clay Tile

Hollow clay tile products with glazed faces typically used to build interior walls.

Glue Laminated Lumber (Glulam)

A structural wood member made by bonding together laminations of dimension lumber.

Glues

Bonding agents made from animal and vegetable products.

Grade

1. Related to soil, the elevation or slope of the ground.

2. In relation to lumber, a means of classifying lumber or other wood products based on specified quality characteristics.

Grade Beam

A ground-level reinforced structural member that supports the exterior wall of a structure and bears directly upon columns or piers.

Grade Level

The elevation of the soil at a specific location.

Grade Mark

A stamp on a product, such as wood, plywood, or steel, indicating the product's capacity.

Gradient

The rate of slope between two points on a surface, determined by dividing their difference in elevation by their distance apart.

Grading

Adjusting the level of the ground on a site.

Grading

The modification of earth to create landforms.

Gravel

Hard rock material in particles larger than 1/4 inch (6.4 mm) in diameter but smaller than 3 inches (76 mm).

Green Lumber

Lumber having a moisture content more than 19 percent.

Greenbelt

A belt-like area around a city, reserved by ordinance for parkland, farms, open space, etc.

Greenhouse Effect

The direct gain of solar heat, generally through south-facing glass walls and roofs.

Grille

An open gate used to cover, conceal, protect, or decorate an opening.

Ground

A conducting connection between an electrical circuit and the earth or a conducting body that serves in place of the earth.

Ground-Fault Circuit Interrupter

A device providing protection from electric shock by de-energizing a circuit within an established period of time when the current to ground exceeds a predetermined value that is less than that needed to activate a standard overcurrent protective device.

Groundwater

Water that exists below the surface of the earth and passes through the subsoil.

Groundwater Level

The plane below which the soil is saturated with water. Also called Groundwater Table or Water Table.

Grout

A viscous mixture of Portland cement, water, and aggregate used to fill cavities in concrete. Also refers to a specially formulated mortar used to fill under the baseplates of steel columns and in connection in precast concrete.

Gusset

Wood or metal plate riveted, bolted, glued or pressed (wood trusses) over joints to transfer stresses between connected members.

Gypsum

Hydrous calcium sulfate.

Gypsum Backerboard

A gypsum panel used as the base on which to bond tile or gypsum wallboard.

Gypsum Board

A gypsum panel used as the base on which to bond tile or gypsum wallboard.

Gypsum Lath

A panel having a gypsum core and a paper covering providing a bonding surface for plaster.

Gypsum Plaster

Ground gypsum that has been calcined and mixed with additives to control setting time and working qualities.

Gypsum Sheathing

A gypsum panel with a water-repellent core. Used for sheathing exterior walls.

Hachure

A shading technique used to depict ground form.

Hardboard

A general term used to describe a panel made from interfelted lignocellulose fibers consolidated under heat and pressure.

Hardness

A measure of the ability of a material to resist indention or surface scratching.

Hardwood

A botanical group of trees that have broad leaves that are shed in the winter (it does not refer to the hardness of the wood).

Hardwood Plywood

Plywood with various species of hardwoods used on the outer veneers.

Haunch

A projection used to support a member, such as a beam.

Header Joist

A structural member fastened between two parallel full-length framing members to support cut off members at the openings.

Heartwood

The wood extending from the pith to the sapwood.

Heat

Form of energy thought to be characterized by the rate of vibration of the molecules of a substance. The hotter the substance, the faster the molecules vibrate. On the other hand, when there is no heat present it is thought the molecules will be at rest, which theoretically occurs at absolute zero, -459.7°F (-273.15°C or 0.0°K).

Heat Exchanger

A device to transfer heat between two physically separated fluids.

Heat Loss

The energy needed to warm outside air leaking into a building through cracks around doors, windows, and other places.

Heat Pump

A heating/refrigerating system in which heat is taken from a heat source, such as the air, and given up to the space to be heated. For cooling, it takes heat from the air in the space and gives it up outdoors.

Heat Quantity (Btu)

Common unit of measure of the quantity of heat is the British Thermal Unit (Btu). One Btu is the amount of heat required to raise one pound of water from 63° to 64°F (1 Btu = 1055.06 J). This is about the amount of heat given off by one wooden match. A pound of coal can produce 13,000 Btu.

Heat Transfer

Heat always flows toward a substance of lower temperature until the temperatures of the two substances equalize. It travels by one or more of three methods: conduction, convection or radiation.

Heat Treating

Heating and cooling a solid metal to produce changes in physical and mechanical properties.

Heat-Strengthened Glass

Glass that has been strengthened by heat treatment.

Heat-Treatable Alloys

Aluminum alloys whose strength characteristics can be improved by heat treatment.

Heating Value

The amount of heat produced by the complete combustion of a unit quantity of fuel.

Heavy Timber Construction

A type of wood-frame construction using heavy timbers for the columns, beams, joists, and rafters.

Heel of Rafter

Seat cut in a rafter that rests on the wall plate.

Hertz

The units of measure of sound frequency, named for Heinrich H. Hertz. One Hertz equals one cycle per second.

Hiding Power

The ability of a paint to hide the previous color or substrate.

Hinge Joint

A joint that permits some action similar to a hinge and in which there is no appreciable separation of the joining members.

Hip Roof

A roof consisting of four sloping planes that intersect forming a pyramidal shape.

Hoistway, Elevator

A fire-resistant vertical shaft in which the elevator moves.

Hollow Brick

A clay masonry unit whose net cross sectional area in the plane of the bearing surface is not less than 60 percent of the gross cross sectional area of that face.

Hollow Clay Masonry

A unit whose core area is 25 to 40 percent of the gross cross-sectional area of the unit.

Hollow Concrete Masonry

Concrete masonry units that have open cores.

Hollow-Core Door

A door with face veneers on the outer surfaces, wood spacers around the edges, and a hollow interior supported with a honey-comb grid.

Holow-Core Slab

A precast concrete structural slab that uses internal cavities to reduce its weight.

Honeycomb

Any substance having cells suggesting a mass of cells such as those built by the honeybee. Some hollow-core doors use the honeycomb principle in their construction.

Horizontal Sheer

The tendency of the top wood fibers to move horizontally in relationship to the bottom fibers.

Hot Melt

Adhesives that bond when they are heated to a liquid form.

HUD

Housing and Urban Development, federal agency.

HUD Mobile Home Standards

Officially, the National Mobile Home Construction and Safety Standards Act of 1974 for construction of mobile homes. Includes the following agencies: DAPIA Design Approval Primary Inspection Agency and IPIA Production Inspection Primary Inspection Agency.

Humidifier

A device used to add moisture to the air.

Humidity

The amount of water vapor withing a given space.

Humidity

The amount or degree of moisture in the air.

HVAC

Heating, ventilating and air conditioning (ASHRAE Guide is the technical reference source).

Hydrate

The capacity of lime to soak up water serveral times its weight.

Hydrated Lime

Calcium hydroxide made by burning calcium carbonate, which forms caclium oxide that can then chemically combine with water.

Hydration

A chemical reaction between water and cement that produces heat and causes the cement to cure or harden.

Hydraulic Elevator

An elevator having the car mounted on top of a hydraulic piston that is moved by the action of hydraulic oil under pressure.

Hydraulic Mortar

A mortar that is capable of setting and hardening under water.

Hydronic Heating System

A system that circulates hot water through a system of pipes and convectors to heat a building.

Hydronics

The science of cooling and heating water.

Hydrostatic Pressure

The pressure equivalent to that exerted on a surface by a column of water of a specified height.

Hydroxide of Lime

The product produced by the chemical reaction during the slaking or hydrating of lime.

Hygrometer

An instrument used to measure humidity conditions of the air.

Hygrometric Expansion

All materials, particularly those of organic origin, expand and contract in relation to their moisture content, which varies with environment. The Hygrometric Coefficient of Expansion is expressed in "Inches Per Inch Per Percent Of Relative Humidity." Example: gypsum board has a coefficient of 7.2 x 10-6 in. per in. per %rh. This means that with an increase in relative humidity of from 10% to 50%, a gypsum board wall 300 ft. long will have an unrestrained linear expansion of 1.0368" or 1&1/32".

Hygroscopic

The ability to readily absorb and retain moisture from the air.

Hz

The abbreviation for hertz, the unit of measurement of the frequency of electric current. It represents the number of cycles per second.