Gas Fill

A gas other than air, usually argon or krypton, placed between window or skylight glazing panes to reduce the U-Factor by suppressing conduction and convection.

Gasket

Material (often rubber) that is installed between two parts to make a joint leak proof.  A resilient or flexible material used between mating surfaces of refrigerating unit parts or of refrigerator doors to provide a leak proof seal.  Any of a wide variety of seals or packings used between matched machine parts or around pipe joints to prevent the escape of a gas or fluid.

Gasket, Foam"

A joint sealing device made of rubber or plastic foam strips.

Gauge

An instrument or device for measuring, indicating or comparing a physical characteristic, i.e., temperature or pressure.

Gauge Manifold

A device constructed to hold compound and high pressure gauges and valved to control flow of fluids through it.

Gauge, Vacuum"

An instrument used to measure pressures below atmospheric pressure

GFCI Ground Fault Circuit Interrupter

An electrical mechanism usually located in a receptacle box or at the main service panel. Measures voltage differential between the hot wire and neutral wire. When a differential is detected, the receptacle or breaker is shut off.

GFI

Ground Fault Interrupter. A safety device used on electrical outlets on exterior outlets on exterior walls, near pools, kitchens and bathrooms to prevent electrical shock.

Gingerbread Work

A term used to describe the excessive use of ornamentation in architecture, especially of a house.

Glass

An inorganic transparent material composed of silica (sand), soda (sodium carbonate), and lime (calcium carbonate) with small quantities of alumina, boric, or magnesia oxides.

Glass Wool Insulation

Material made of glass fibers, usually in the form of blankets wrapped in heavy asphalt-treated or vapor-barrier paper.

Glazier's Points

Small metal pieces used to hold a glass pane in a wooden window sash until putty is applied.

Glazing

The glass or plastic panes in a window, door, or skylight.

Glazing Bead

A molding or stop around the inside of a window frame to hold the glass in place.

Good

In above-average condition given its age and function, showing less than normal sign of wear and/or usage.

GPM

Gallons per minute

Grade

The ground level existing at the outside walls of a building or elsewhere on a building site.

Grade ( Lumber Grade)

The designation of the quality of a manufactured piece of wood.

Grade (Finish Grade)

A reference plane representing the average finished ground level adjoining a structure.

Grade (Natural Grade)

A reference plane representing the undisturbed natural ground level adjoining or around a structure.

Grading

A sloping of the grounds immediately adjacent to a building. Proper grading causes water to flow away from a structure. Grading can be accomplished either with machinery or by hand.

Grain

The direction, size, arrangement, appearance or quality of the fibers in wood.

Granules

Ceramic, color-coated crushed rock that is applied to the exposed surface of asphalt roofing products.

Graphite

Fine black lubricating powder used dry or mixed with oil.

Green Lumber

Lumber which has not been dried or seasoned

Greenhouse Window

A three-dimensional window that projects from the exterior wall and usually has glazing on all sides except the bottom, which serves as a shelf.

Ground

To connect any part of an electrical wiring system to a ground, either a cold water pipe or a long metal rod driven solidly into the soil, to keep metal parts of wiring system at zero volts.

Ground Floor

The floor of a building that is approximately level with the ground.

Grout

A thin, fluid mortar used to fill small joints and cavities in masonry work.

Gutter

The trough that channels water from the eaves to the downspouts.

Gypsum Board

Large panel composed of a fire-resistant gypsum core sandwiched between two layers of heavy paper and used as a finish for walls and ceilings, or as a backing for other wall and ceiling material.

Halide Refrigerants

The family of refrigerants containing halogen chemicals.

Halide Torch

A type of torch used to detect halogen refrigerant leaks. Hastelloy-trade name for a hard, noncorroding metal alloy.

Hall

A room at the entrance of a building or a passage that provides access to various parts of a building.

Hardware

The metal fittings of a building e.g., hinges, locks, lifts, doorknobs.

HARV/HVAC/HVACR

Heating, air conditioning, refrigeration, ventilation. A catch acronym for the four areas of mechanical engineering. It refers to the heating, air conditioning and duct work components.

Hatchway

A lifting or sliding door in a ceiling that gives access to an attic a similar door in a floor, giving access to a cellar.

HCFC

An acronym for Halogenated Chlorofluorocarbon, which is a family of refrigerants that if released into the atmosphere are destructive to the Earth's ozone layer

Head Jamb

A piece of finish material placed across the underside of the top of a door or window opening.

Head Lap

Shortest distance form the butt edge of an overlapping shingle to the upper edge of a shingle in the second course below. The triple coverage portion of the top lap of strip shingles.

Head Pressure

A pressure which exists in condensing side of refrigerating system.

Head Pressure Control

A pressure operated control which opens electrical circuit if high side pressure becomes excessive.

Head Track

The track provided at the head of a sliding glass door. Also, the head member incorporating the track.

Head, Velocity"

In flowing fluid, height of fluid equivalent to its velocity pressure.

Header

The upper horizontal member of a window frame. Also called head.  A framing member which crosses and supports the ends of joists.

Hearth

The floor of a fireplace. The front hearth extends out into the room and may be of brick or decorative stone the back hearth is inside the fireplace and usually made of firebrick.