A single (or double) operating window in which the bottom of the sash swings outwards for ventilation


The exterior center post or moulding on a double door (attached to the secondary or inactive door panel)


Three connected windows (usually made up of a larger fixed window in the center and two smaller operating windows on either side) in a 30 degree or 45 degree angle formation


Four or more connected windows (fixed or operating) in a 10 degree or 15 degree angle formation


An exterior moulding around the window (to seal and cover the exposed window opening, insulation, interior jambs etc…)


The interior decorative moulding/trim that covers the inside edge of the jambs and the rough openings between the window and the wall

Double glazing

The use of two panes of glass (in a window frame) to increase energy efficiency and to provide other performance benefits

Double hung

A window with two vertical operating sashes that slide up-and-down for ventilation

Drip cap

An exterior aluminum moulding placed on the top of the brickmould or capping of a window frame

Egress window

A window large enough for exit in case of an emergency


Non-opening or non-operating window


Aluminum attached to the outside of the head or side jambs of a window to provide a weather barrier (preventing leakage between the frame and the wall)


A weatherstrip used to create a watertight seal between the sash and the window frame


The glass panes in the sash of a window

Glazing stop

The moulding (or part of the window sash) which holds the glass in place


A bar used to visually separate glass into multiple lites (also named internal grid, muntin bar or window pane divider)


A heavy beam extended across the top of the rough opening to help support the weight of the building


Glazing framed by muntin bars and/or sash in a window or door

Low-E glass

A commonly used term referring to a low emissivity coating placed on the glass surface to restrict the passage of radiant heat


A trim installed around the exterior perimeter of a window frame


The connectors installed between individual windows in a multiple unit window


A bar used to visually separate glass into multiple lites (also named internal grid, grill or window pane divider)


A metal arm and gear which allows for easy opening or closing of projecting windows


The degree of the slope in a roof


The horizontal parts of a window sash or door panel

Rough opening

The opening in a wall to accommodate the installation of a window or door

Sash balance

A system of weights or coiled springs which assist in the raising and lowering of single hung and double hung windows


A wooden board installed on the bottom contour of a bow or bay window (to provide a seat or shelf space)


Wooden wedges that are used to secure and level windows in the rough opening


Tall and narrow fixed glass on either (or both) sides of an entry door


The horizontal part that forms the bottom of a window or door frame

Sill course

The row of bricks across the bottom of a rough opening

Simulated divided lite

A method of constructing windows in which grills are attached to the inside and outside of glass panels to simulate the look of true divided lites

Single Hung

A window in which the top sash is fixed (or inoperable) and the bottom sash slides vertically up-and-down for ventilation

Solar gain

The amount of heat which has passed through the glass of windows and doors and has collected inside of the home


Wood installed vertically and horizontally to build a frame or wall


A smaller window attached above a door or another window

Triple glazing

A window glazed with three panes of glass (enclosing two separate air spaces)


A measure of heat transmission through a wall or window (the lower the U-Factor, the better the insulating value)

Vapor barrier

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

Venting unit

A window or door that opens or operates

Wind Load

Force exerted on a surface by moving air