WindowAnatomyGlossary

bow window

A curved window, sometimes called a circular bay

stool

A horizontal board or plate at the window sill on the inside of the window, fitted against the bottom rail of the lower sash to form a base for the casing.

parting bead

A long narrow strip between the upper and lower sashes in a double-hung window frame, enabling them to slide past each other.

apron

A piece of casing or decorative trim installed against the wall immediately beneath the stool of a window.

clerestory window

A shallow window set near the ceiling. Usually should be decorated inconspicuously. In modern architecture, it is sometimes placed in the slope of a beamed ceiling, in which case it should rarely be decorated at all.

pane

A single sheet of glass in a window or a door.

weep (weephole)

A small space intentionally designed into the bottom rail of any exterior window covering to allow condensate to drain and not accumulate.

muntin

A strip of wood or metal separating and holding panes of glass in a window.

seasonal film

A temporary, clear, plastic sheet fastened or adhered to interior window trip to improve the airtightness of drafty prime windows (in contrast to window film).

window panel

A tracked-operable or fixed-inoperable glass window installed on the interior to supplement the performance of the prime window.

lucarne

A type of dormer window.

lite

A unit of glass in a window.

palladian window

An arched top window with straight panes below the arch.

side jamb

An upright piece or surface forming the side of an opening (as for a door, window, or fireplace).

window retrofit

Any change to an existing window including window replacement, window repair, and the addition of window coverings.

roof window

Any window mounted on a roof rather than in a wall; same as skylight.

single hung window

Any window or window covering with two sashes or glass panels and only the bottom of the two operable.

corner window

Any window that comes together at the corner of a room.

hung window

Any window with sash(es) that move up and down and that resist gravity/make adjustment easier by being balanced or hung using counterweights or springs.

gas fill

Argon, xenon, or krypton gas sealed between the panes of insulated glazing units (IGU). These gases are used because they exhibit less convective heat transfer than air.

sash lock

Attached to the sashes of a double hung window that can fix both in the shut position.

window schematic

Broad schematic of the window.

egress

Emergency Exit

double tracked

For storm windows and window panels, three panels - two glass and one insect screen - with the top panel being fixed in place and the lower glass panel and insect screen operating in tracks in the frame.

photochromic

Glass or glazing that changes from clear to dark based on sunlight levels (versus electrochromic or thermochromic).

thermochromic

Glass that changes from clear to dark based on temperature (versus electrochromic or photochromic).

electrochromic

Glass that changes from clear to darkened (and back) based on electrical current (versus thermochromic or photochromic).

rail

Horizontal element of the sash frame.

bottom rail

Horizontal part of the window sash at the sill.

jalousie window

Identified by narrow, horizontal strips of glass that open by means of a crank to any desired angle. Decorating problems result only when the shape or location is unusual.

meeting rail

In a double-hung window the rail of each sash that meets a rail of the other when the window is closed.

double hung window

Most common of all window types, has two sashes, one or both of which slide up and down. Unless it is too long and narrow or in the wrong location, this type of window is usually one of the easiest to decorate.

applied film

Most commonly, flexible plastic sheet applied directly and permanently to glass to improve the window's optical and/or thermal performance.

ranch window

Most often a wide window set high off the floor. Usually has sliding sashes and is common to most ranch type houses. It requires special consideration when decorating to make it attractive.

slanting window

Often called "cathedral" window, usually an entire wall of the room. Its main characteristic is the angle at the top where the window follows the line of a slanting roof. This top slanting line often causes decorating concern, but the problem can be solved very effectively.

picture window

One designed to frame an outside view. It may consist of one large, fixed pane of glass, in which case the window cannot be opened. Or it may have movable sections on one or both sides of a fixed pane - or above and below - which can be opened for ventilation. Sometimes there are decorating problems, but in general, a picture window is your big opportunity.

in swinging casement

Opens into the room. If it is not decorated properly, curtains and draperies may tangle with the window as it is opened and closed.

out swinging casement

Opens outward. Both in-swinging and outswinging casements may be operated by a crank, or simply moved by hand. Out-swinging casements are easily decorated.

jamb

Parts of window frame facing into the window opening, at sides and top.

tinted

Referring to applied films when they are darkened to reduce direct sunlight and glare. Tints are available as either low or high solar gain.

security

Referring to window attachments that improve the protection of the primary window.

scuncheon

Refers to the inner part of a door jam or window frame.

double window

Side by side windows. (If there are more than one they are often called multiple windows). Most often treated as a single unit, always think of them together, as one decorating element.

french door

Sometimes called French windows. they come in pairs and often open onto a porch or patio. Usually they need special decorating to look their best.

grilles

Surface-mounted plastic cosmetic grids simulating the muntins in true divided lite windows.

exterior sill

The bottom horizontal element of the window frame, often sloped outward for drainage.

sash

The moveable part of a window made up of the vertical and horizontal frame that holds the glass.

check rail

The sash frame parts of a hung window where the two sashes meet; also called the meeting rail.

head jamb

The top member of a frame.

stile

These are the main vertical members in the framework of a sash, found at the sides of a window.

awning window

These windows are hinged at the top and open outward, allowing for ventilation even during a light rain. Often used in combination with other window styles or placed higher on walls for privacy, these windows are easy to open and close. Has wide, horizontal sashes that open outward to any angle; can usually be left open when its raining. Unless it is awkwardly placed or shaped, it's an easy one to decorate.

fanlight

This accessory is a semicircular window set above a door or other window. This accessory allows natural illumination into a room and adds a graceful, elegant touch to traditional decor.

single pane clear

This glass is commonly found in older homes, provides the weakest thermal performance but highest visual transmittance.

prime window

This is the existing window to which window coverings are added to improve overall performance.

mullions

This item is a vertical element that forms a division between units of a window, door, or screen, or is used decoratively. When dividing adjacent window units, its primary purpose is to provide structural support to an arch or lintel above the window opening. Its secondary purpose may be as a rigid support to the glazing of the window. When used to support glazing, they are often teamed with horizontal elements called "transoms" which divide an opening's upper part into one or more additional lights.

high solar gain low-e

This low-e coating improves energy performance and is designed for colder climates where heating systems dominate. These windows are designed to reduce heat loss but admit solar gain. Although currently these coatings are applied mainly to glass, they can be applied to clear plastic polymer panels as well.

double pane with low-e

This pane provides high resistance to heat loss and can be tuned for solar gain but with some loss of visual transmittance.

double pane clear

This pane provides strong thermal performance: good resistance to heat loss, high solar heat gain, and high visual transmittance.

bay window

Three or more windows set at an angle to each other in a recessed area. You can use lots of imagination with bay windows.

triple pane

Three panes of glass and two sealed gas spaces.

sliding glass door

Today's functional version of French doors. They are often set into a regular wall but are sometimes part of a modern "glass wall." Either way, they need special decor that allows them to serve as doors yet provide nighttime privacy.

clear rigid polymer

Transparent sheer material used most often in interior window panels in place of glass.

dormer window

Usually a small window projecting from the house in an alcove-like extension of the room. It requires a treatment all its own.

divided light

Window glass separated by small frames within the sash.

casing

Window trim (covers space between framed opening and window unit).

casement

Window type hinged on the side, most commonly swinging out.

double pane

Window unit with two panes of glass sealed into a glazing unit; gas between the panes is trapped (also called an insulated glazing unit - IGU).

insulated glass unit (IGU)

Window unit with two panes of glass sealed into a glazing unit; gas between the panes is trapped (also called double-glazing).

fenestration

Windows and doors or their placement in buildings.