Windows elevate our everyday by bringing in natural light while keeping away harmful insects and controlling adverse weather conditions. Windows are tiny parts of a house, but the window terminologies can be overwhelming, especially for non-industry players. That’s why we’ve taken it upon ourselves to explain some of the technical window terminologies we use in new construction, remodels, and replacement projects.
Common Window Terms Explained
AAMAAmerican Architectural Manufacturers Association. The nonprofit trade association that sets quality standards and provides various educational programs and events for the window, door, and skylight manufacturers.
Annealed GlassAnnealed glass is manufactured by slowly cooling to relieve internal stress and prevent cracking when exposed to temperature changes. Unlike tempered glass, annealed glass often breaks off in large, sharp pieces hence not suitable for high traffic areas or windows accessible by young kids. They are great for basement windows because they’re relatively cheaper than tempered glass.
Air Infiltration (Air-Leakage)The measure of the amount of air leakage passing in and out of a building’s structure through windows, doors, skylights, poorly sealed access plumbing access points, siding cracks, etc.
Air-Leakage RatingA measure of the rate at which air is leaking around a door or window or door. The measurement is calculated based on the building’s relative interior to exterior air pressure. The rating is used to determine how air-tight the building’s doors and windows are.
Ambient TemperatureThe environmental temperature of the immediate surroundings.
Argon GasArgon is a gas fill used by window manufacturers for displacing the air trapped between the panels in windows. Constituting about 1 percent of the Earth's atmosphere, Argon is non-toxic, clear, odorless, and inert.
Astragal BalanceA vertical hardware piece designed to be fastened to a door for the purpose of sealing the gap between double doors when the doors are closed.
Basement WindowAny window located in a basement for the purpose of light or ventilation of the space.
BalanceA window balance refers to the hidden window components fitted inside the window frame. They are only used in single windows or double hangs to assist you with the sash’s weight when closing or opening the window.
Bay WindowAn assemblage of a picture window between two smaller windows that are angled to create a bay space on the interior side.
Bottom RailThe horizontal section at the bottom of a window sash.
Bow WindowAn assemblage of four or more windows positioned to form an arch-shaped window unit bowing outward from a building.
BrickmoldA molding designed to use as the casing for the exterior side of a window or door.
Blind stopA blind stop is a rectangular molding used in the construction of window frames. It’s often nailed between the outside sashes and the outside trim piece and serves to stop the sash or the screen.
Cam LockA cam lock is a small piece that pulls together your window sash to keep the window locked and secure. They’re available on both single hung and double hung windows.
CasingA casing is a piece of molding often used to trim the window’s perimeter. Cases are narrower but much thicker than base moldings.
Cable Support KitA set of hardware made for anchoring a bow or bay window to a building’s structure. The kit is designed to support the part of the window that extends outward to prevent it from sagging.
Casement WindowA window with hinges on both the interior and exterior sides, designed so that the sash swings open in the outward direction for ventilation.
CaulkingA construction compound made for sealing crevices to prevent air or water leaks.
CondensationThe accumulation of water on a window, wall, drinking glass, or other surfaces due to humidity in warm air converting to water droplets when it meets the colder surface.
CorrosionThe process or effects of deterioration of stone, metal, or other material from a chemical reaction due to exposure to moisture, weather conditions, corrosive chemicals, or other causes.
CladdingWindow cladding refers to wood windows enclosed in another material or made with an external application of another material like aluminum, vinyl, PVC, or fiberglass.
CompositeComposite windows are manufactured with several different materials in a compact combination to give the window the look and benefits of many window types.
CondensationInterior window condensation occurs when there is excessive moisture in the house, usually during winter. Exterior condensation occurs when the window surface is cooler than the dew point.
ConductionConduction is one way through which heat passes through the window and involves the passing of heat through a solid material (window frame and glass) from molecule to molecule.
ConvectionConvection is the heat transfer through the movement of gases or liquid. Warm air in the room touches the cold window and cools down and sinks, which creates a convection current of air around the window.
Double GlazingDouble glazing is sometimes referred to as Insulating glass (IG), and consists of 2 or 3 glass window panes that are separated by a gas-filled space or vacuum to minimize heat transfer across the window.
Double Hung WindowOn a double-hung window, both sashes in the window frame are operable by moving up and down. They allow the sashes to tilt easily for easy cleaning.
EgressEgress windows are large windows that allow room occupants to enter or exit during an emergency. They’re required when finishing a basement and are often attached to ladders or steps for an easy escape.
ENERGY STAR® Certification ProgramENERGY STAR® Certification Program streamlines window manufacturing by ensuring that windows are manufactured by ENERGY STAR qualified windows manufacturers and the products are independently tested, verified, and certified by the National Fenestration Rating Council (NFRC).
ExtrusionThis is a process of extruding molten raw material through a set of metal blocks (dies) to produce a vinyl profile that is then cut into specific lengths and welded together to form a window system.
FenestrationFenestration is a term used to refer to the design, construction, or openings in a building. They include windows, doors, wall panels, vents, storefronts, louvers, and much more.
Window HeadThis is the main horizontal part that forms the top of a window frame.
Insulating GlassInsulating glass (IG) comprises two or more window panes separated by an insulating material like a vacuum or gas.
GlazingThis is a putty or glazing compound that holds the window glass in place and seals off external weather conditions.
GrillesWindow Grilles refer to decorative patterns on a window or door and consist of horizontal and/or vertical bars dividing larger sheets of glass into smaller window panes.
Jamb linerA jamb liner is helpful for extending the interior of your window so as to cover the thickness of the walls and transition between your interior trim and the window.
Krypton GasKrypton is a non-toxic, odorless, colorless gas that is used in place of air between window panes to improve insulation and energy efficiency.
Lead Safe Window ReplacementLead safe is a certification requires as per the federal government law passed in April 2010 that requires all homes constructed before 1977 to adhere to practices that ensure minimal exposure to harmful Lead.
Low E GlassLow E Glass is manufactured with advanced technology to keep your home warm during winter and cool during summer. The glass comes with 3 coats of silver on the outside to insulate your home from the outdoor conditions.
MullionA mullion refers to a vertical element that divides different window or door units and is mainly meant for decoration.
National Fenestration Rating Council (NFRC)The NFRC serves to provide doors and windows retailers with facts sheets to educate their clients during purchase.
Obscure GlassIt’s any type of rolled glass with an embedded pattern on its surface. Some types come as painted or laminated glass used for decoration purposes.
PaneA pane refers to the glass part of a sectioned window.
PlumbA plumb refers to the vertical planes in a window.
R-ValueR-value is the resistance of a window to heat conduction and is expressed as the inverse of the U-factor.
RailRails fit between the vertical components of a window. They are the horizontal members of the sash.
Replacement WindowThis is a window that is fitted to an existing window opening to replace the existing window.
RetrofitA retrofit window is installed into an existing window frame.
Roller CamsThese are universal products that suit most UPVC profiles of window or door locking systems to provide a secure locking point.
SidelightA sidelight is a window with a vertical emphasis, usually flanking a door or a larger window.
Slider WindowA sliding window is utilized in wider and shorter openings. The windows often open sideways with one pane sliding over the other.
Solar Heat Gain CoefficientAbbreviated as SHGC, Solar Heat Gain Coefficient denotes the fraction of solar radiation that goes through the window. It is usually expressed as a decimal number between 0 and 1.
Tilt and Turn WindowsTilt and turn windows operate in two ways. As the tilt opens the top of the sash towards the inside for ventilation, the turn creates an opening side hung to the inside.
Window SashA window sash comprises one or more movable panels that hold panes of glass.
Sash LockThis is a window latch and keeper used to lock sliding windows.
OperatorA windows operator features a worm gear driving mechanism with a steel arm and is often used in steel-framed windows.
Side JambA side jamb is the side-post or lining on a window or doorway.
Single Hung WindowsA single hung window has the top sash fixed in place and does not move while the bottom sash is freely operable.
Tempered GlassTempered glass is a tough safety glass that is 4-5 times harder than regular glass and is made under extreme heating followed by rapid cooling. When it breaks, it shatters into little pebbles that pose less danger.
Vinyl-Clad WindowVinyl-clad windows are made with wood interiors with an external vinyl cover to improve durability and longevity while giving the interior the aesthetic finish of the wood.
U- FactorU- Factor is the measure of the rate at which heat is transferred across the window and tells how well the window insulates. It ranges between 0.25 and 1.25 and is measured in Btu/h.
Warm-Edge TechnologyWarm Edge technology uses spacer bars to insulate the edges of sealed window units to keep the panes of glass apart and reduce heat loss.
Weep holeThis is a tiny hole located at the bottom edge of a storm-window frame to drain off water from the window and prevent the wood from rotting or steel from rusting.