The window glossary.

Argon

A colorless, safe gas used between the panes of insulated glass because it conducts heat more slowly than air.

Awning window

A window hinged at the top that opens outward from the bottom, often used for ventilation in light rain.

Bay window

A trio of windows set at angles that projects outward from the wall.

Bow window

A curved window of four to six panes that projects outward in a gentle arc.

Casement window

A window hinged at the side that swings open like a door, usually with a crank.

Clad

A wood window covered on the outside with a protective layer of aluminum or vinyl.

Condensation

Moisture that forms when warm, humid air meets a cold surface, such as the inside of a window in winter.

Double-hung window

A window with two sashes that slide up and down, and that usually tilt in for cleaning.

Egress window

A window large enough for a person to climb out in an emergency, required for many basement bedrooms.

Flashing

Waterproof material around an opening that directs water away from the wall.

Full-frame replacement

Replacing the whole window, including the frame, so the opening can be repaired, flashed and insulated.

Glazing

The glass in a window or door, or the act of installing it.

Grid

Bars that divide a window into smaller panes, also called muntins or divided lites.

Insert replacement

A new window unit fitted inside the existing frame, keeping the trim in place.

Jamb

The vertical sides of a window or door frame.

Laminated glass

Two layers of glass bonded to a tough plastic interlayer, used for strength, security and quieter rooms.

Low-E

Low-emissivity: a nearly invisible coating that reflects heat while letting light through.

Mullion

A vertical or horizontal bar that joins two windows into one unit.

Nailing fin

A flange around a new-construction window that fastens to the wall framing.

Rough opening

The framed hole in the wall where a window or door is installed.

Sash

The movable part of a window that holds the glass.

Sill

The horizontal surface at the bottom of a window opening.

SHGC

Solar heat gain coefficient: the share of the sun's heat that passes through a window. Lower blocks more heat.

Spacer

The strip around the edge of insulated glass that holds the panes apart and seals the gap.

Tempered glass

Heat-treated glass that is stronger than ordinary glass and breaks into small pieces.

U-factor

A measure of how fast heat moves through a window. Lower is better insulation.

Weatherstripping

Flexible seals around a sash or door that block air and water.

Weep hole

A small opening at the bottom of a window frame that lets water drain out.

No term matches that search. Call us and we will explain it.