A Glossary Of Terms To Help You Shop For Windows

Regardless of where you shop for windows, it will be a lot easier if you know what to ask for, and what each term means. Take a minute to read through some of these terms and familiarize yourself with “window vernacular” and then shop like a pro from A to Z

A

American Made Windows

American Made Windows manufactures all windows right here in the USA, providing jobs for Americans and a quality product for homeowners.

Annealed Glass

Annealed glass is brittle and breakable, but is easy to cut.

Argon Gas

Argon is a safe, odorless, colorless, non-toxic, non-flammable inert gas that is commonly used in place of air between the glass panes of an insulated Low-E glass unit.

Astragal

The center member of a double door, which is attached to the fixed or inactive door panel.

Awning Window

A window unit in which the bottom of the sash swings outward.

B

Balance

A mechanical device, normally spring loaded, used in hung windows to counterbalance the weight of the sash during opening and closing. Three types used in vinyl windows Spiral, Block & Tackle and Constant Force.

Bay Window

A composite of three windows (casement, double hung or picture windows) usually made up of a large center unit and two flanking units at 30, 45 or 90-degree angles to the wall.

Bead

A molding or stop placed around a window frame to hold the glass in place by pressure.

Bow Window

A composite of four or more window units in a radial or bow formation at a 10 or 15-degree angle.

Brickmold

A type of external casing which frames windows and doors.

C

Casement Window

A window unit in which the single sash cranks outward, to the right or left.

Casing

Molding of various widths, thickness and shapes applied to the interior framework of window and door units

Check Rail

On a double-hung window, the bottom rail of the upper sash and the upper rail of the lower sash, where the lock is mounted, also known as the meeting rail.

Cladding

Any material locked to the outside faces of doors and windows to provide a durable, low-maintenance exterior surface.

Condensation

When the air inside an enclosure is warmer than the air outside the enclosure, the moisture vapor in the interior air will condense, creating small water droplets at the intersection of dissimilar materials.

Cottage Window

A double-hung window in which the upper sash is shorter in height than the lower sash. Opposite of an oriel window.

D

Dormer

A space which protrudes from the roof of a house, usually including one or more windows.

Double or Dual Glazing

Use of two panes of glass with an overall thickness of 1” or less in a window or door to increase energy efficiency and provide other performance benefits.

Double-Hung Window

A window unit that has two operable sashes which move vertically in the frame. ViWinTech double-hung windows also tilt in for easy cleaning.

Drip Cap

A molding or extrusion placed on the top of the head jamb, top brickmold, or casing of a window frame.

E

Egress Window

A window with specific release hardware and a minimum clear opening size to allow occupants to escape through the window in case of a fire or large enough for a fireman with an air-pac to enter.

Each emergency escape and rescue window shall have a minimum net clear opening of 5.7 square feet (with bottom sash up and not removed). The minimum clear height dimension shall be 24 inches. The minimum clear width dimension shall be 20 inches. The maximum sill height shall not be more than 44 inches from the floor.

Emax Plus® Glass

Emax® Glass with a safe, odorless, colorless, non-toxic, non-flammable inert gas that is commonly used in place of air between the glass panes of an insulated unit, adding additional insulating value to the glass unit.

Emax® Glass

A transparent coating applied to a glass surface to separate longwave (heat) energy and shortwave (light) energy. The long wave (radiant heat you feel) is reflected back to the heat source (outside in summer, inside in winter). The shortwave (light) is allowed to pass through the coating

Extrude

The process of shaping aluminum or vinyl by forcing it through a die.

Extrusion

A form produced by forcing material through a die. Most vinyl window frames, sashes and vinyl accessory parts are extrusions.

F

Fenestration

An architectural term referring to the arrangement of windows in a wall. From the Latin word, “fenestra,” meaning window.

Fixed Window

Non-venting or non-operable window. Also known as a picture window.

Flashing

A thin strip of metal or synthetic material that diverts water away from a window or skylight.

Frame

The enclosure in which window sash or door panels are mounted.

French Hinged Door

Hinged door(s) which have wider rail and stile members around the glass.

French Sliding Door

A sliding door which has wider rail and stile members around the glass, giving the appearance of a French hinged door.

G

Geometrics

Windows made in architectural shapes such as trapezoids, ellipses, half rounds, circles, etc.

Glass Surface Numbers

A numbering system to identify glass surfaces. They always start from the exterior. For example, a regular insulating glass unit (IGU) has four surfaces:

#1 = the outside surface of the exterior lite;

#2 = the inside surface of the exterior lite;

#3 = the outside surface of the interior lite;

and #4 = the inside surface of the interior lite.

Glazing

Glass in a window or door; the act or process of fitting with glass.

Glazing Bead

A vinyl strip applied to the window sash around the perimeter of the glass.

Glazing Stops

The part of the sash or door panel which holds the glass in place.

Grids

A term referring to window pane dividers or muntins, usually a type of assembly which may be removed (exterior mounted) or between the glass. either for ease of cleaning. Also called grilles.

H

Head

The main horizontal member forming the top of the window or door frame.

Header

A horizontal framing member placed over the rough opening of a window to prevent the weight of wall or roof from resting on the window frame.

Hopper

A window unit in which the top of the sash swings inward, most often used as a basement window.

Hung Window

A window in which the operating sash(es) move up and down within the master frame. The weight of each operating sash is counterbalanced with balances to permit easy operation.

I

Insulating Glass (IG)

Insulating glass is made up to two lites of glass separated by a spacer around the perimeter, with a sealant plied to bond the plates to the spacer to form a sealed unit. Insulating glass is common in multi-story office buildings and is being used more often in residential construction. For hurricane protection, insulating glass provides the added benefit of placing two panes of glass, with the interior pane being laminated, between building occupants and exterior elements. Also, as hurricane-resistant code requirements move north, insulating glass is necessary to meet thermal requirements.

J

Jamb

The main vertical members forming the sides of a window or door frame.

Jamb Liner

In a modern wood double-hung window, the track installed inside the jambs on which the window sashes slide.

K

Knocked Down (KD)

Unassembled window or door unit.

L

Laminated Glass

Laminated glass is used in most blast-resistant and hurricane-resistant glazing. This type of glass is composed of a glass “sandwich” of two bonded plates of glass with a plastic interlayer between them. Laminated glass may fracture, but fragments remain bonded to the interlayer and in place inside the window if properly glazed.

Lift

A handle or grip that is applied or is an integral part of the bottom rail of the lower sash (top rail of the upper sash) of a double-hung window to make it easier to raise or lower the sash.

Light or Lite

Glazing framed by muntins and/or sash in a window or door.

Light Shaft

An insulated shaft built to direct the light from a roof window or skylight through the attic to the room below.

Low E Glass

A transparent coating applied to a glass surface to separate longwave (heat) energy and shortwave (light) energy. The long wave (radiant heat you feel) is reflected back to the heat source (outside in summer, inside in winter). The shortwave (light) is allowed to pass through the coating

M

Masonry Opening

The space in a masonry wall left open for windows or door.

Mortise

A slot or rectangular cavity cut into a piece of wood or vinyl to receive another part.

Mortise and Tenon

A strong wood or vinyl joint made by fitting together a mortise in one board or extrusion and a matching projecting member (tenon) in the other. Found most often in wood windows and mechanically fastened (not welded) vinyl windows.

Mullion

A wood, vinyl, metal (or a combination of the three) part used to structurally join two window or door units.

Muntin

Applies to any short or light bar, either vertical or horizontal, used to separate glass in a sash into multiple lites. Also called a grille or grid.

Muntin Bar

Any small bar that divides a window’s glass. Also called a grille or windowpane divider.

O

Obscure Glass

Mainly used for decoration, diffusion, or privacy. The pattern is rolled into the hot glass during glass manufacturing.

Oriel Window

A double-hung window in which the lower sash is shorter than the upper sash. Opposite of a cottage window.

P

Pane

A framed sheet of glass within a window.

Parting Stop

In a double-hung window, a strip of wood applied to the jamb to separate the sash.

Passive Solar Collector

Any glazed area in the walls or roof of a building pointed to the south to take maximum advantage of the sun’s heat without a mechanical (or active) method of storage or distribution of the heat.

Picture Window

Non-venting or non-operable window. Also known as a fixed window.

PSF

pounds per square foot – a measurement of air pressure used in window testing, e.g., 1.56 psf (25 mph) or 6.24 psf (50 mph).

R

R-Value

Resistance to thermal transfer or heat flow. Higher R-value numbers indicate greater insulating value. R-value = the number 1 divided by the U-value.

Rail

The top and bottom horizontal members of the framework of a window or door sash.

Rough Opening

The framed opening in a wall into which a window or door unit is to be installed, typically ½” larger than the unit size of a door or window in new construction.

S

Sash

A single assembly of stiles and rails made into a frame for holding the glass.

Sash Balance

A system of weights, cords and/or coiled springs which assist in raising double-hung sash and tend to keep the sash in any placed position by counterbalancing the weight of the sash.

Sash Cord

In double-hung windows, the rope or chain which attaches the sash to the counterbalance.

Sash Lift

A handle or grip that is applied or is an integral part of the bottom rail of the lower sash (top rail of the upper sash) of a double-hung window to make it easier to raise or lower the sash.

Sash Weights

In older double-hung windows, the concealed cast-iron weights which are used to counterbalance the sash.

Screens

Usually mounted on the window or door exterior, depending on sash, vent, or panel operation. Screens provide ventilation and transparency and are usually one of three types: insect screens to resist insects, protection screens to resist glass breakage and casual vandalism, or security screens to resist forced entry or escape.

Seat Board

A flat board cut to fit the contour of a bow or bay window and installed between the sills and the flat wall surface, providing a seat or shelf space.

Shims

Wood wedges (often wood shingles) used to secure the window or door unit in the rough or masonry opening in a square, level and plumb position during and after installation.

Sidelights

Narrow fixed units mulled or joined to door units to give a more open appearance.

Sill

The main horizontal member forming the bottom of the frame of a window or door.

Simulated Divided Light

A method of constructing windows in which muntins are affixed to the inside and/or outside of a panel of insulated glass to simulate the look of a true divided light.

Single Glazing

Use of single panes of glass in a window. Not as energy-efficient as double glazing.

Single-Hung Window

A type of window in which the top sash is fixed or inoperable.

Sliding Patio Door

A door in which the operating panel slides sideways within the master frame. Each operating panel has rollers to permit easy operation. Also called a patio door. Usually used in applications where passage to exterior patios is required while providing weather resistance and security. Not to be confused with mall or entrance sliding doors which provide security, but little or no weather resistance. Also called a sliding glass door.

Sliding Window

A window in which the operating sash slide sideways within the master frame. Each operating sash has glides or rollers to permit easy operation. Also called gliders or gliding window.

Sloped Sill Adapter

Used to cover the gap between the old sloped sill window and the new block frame window. It adapts a new window to the existing sloping sill. Used in replacement window applications.

Solar Gain

The process of providing a net heat gain within a structure, over and above the normal heat loss, by the passive collection of the sun’s heat through windows and other glazed areas.

Solar Heat Gain

Coefficient Measures the amount of radiant heat transfer from the sun through a window. The lower the number means the less amount of solar heat transfer through the window (lower is better in the south). CT (SHGC).

Measures the amount of radiant Systems SHGC = .27, this equates to a 48% thermal.

SpaceX

Elon Musk’s space exploration company. Nothing to do with windows, we just wondered if you were actually reading all the way through this glossary. 🙂

Stile

The main vertical members of the framework of a window or door sash.

Stop

A molding used to hold, position or separate window parts.

T

Tempered Glass

Tempered and heat-strengthened glass is less brittle, but cannot be cut. These types of glass can be up to two-to-four times stronger than annealed glass. If tempered glass is broken, it disintegrates into small fragments. For this reason, tempered glass is commonly used in swinging doors, sliding patio doors and storefront windows.

Tenon

A rectangular projection cut out of a piece of wood or vinyl for insertion into a mortise.

Thermal Break

The addition of a thermally insulating material between two thermally conductive materials.

Transom

A small window that fits over the top of a door or window, primarily for additional light and aesthetic value.

True Divided Light

A term which refers to windows in which multiple individual panes of glass or lights are assembled in the sash using muntins.

U

U-Value

The rate of heat flow-value through the complete heat barrier, from room air to outside air. The lower the U-value, the better the insulating value. This is a better tool to use when comparing window insulating performance.

Unison Lock

A casement locking system which secures the window at two locking points by operation of one handle.

United Inches (UI)

The sum total of one window width and one window height expressed in inches. (i.e. 36” x 52” window = 88 u.i.)

V

Vapor Barrier

A watertight material used to prevent the passage of moisture into or through floors, walls, and ceilings.

Vent Unit

A window or door unit that opens or operates.

Vinyl

A plastic material used for cladding or entire window units.

W

Weather Stripping

A material or device used to seal the openings, gaps or cracks of venting window and door units to prevent water and air infiltration.

Weep Slot or Weep Hole

An opening in a window sill and/or sash rail to allow water to drain to the exterior.

Windload

Force exerted on a surface by moving air.

Window Size

Always expressed as width first, then height.

Window Style

The description of the way a window operates, e.g., hung, sliding, casement, etc.

X

XO Sliding Window

Since “O” indicates the fixed sash, this is a window in which the left sash slides and right sash is fixed, looking from the outside in.

XX Sliding Window

Since “X” indicates the moving sash, this is a window in which both sash operate.

Leave a Comment