(613) 738-9500
Mon-Fri 8am-5pm | Sat 9am-4pm 855 Industrial Ave, Ottawa

Window & Door Glossary

Understanding window and door terminology helps you make informed decisions. Here's a plain-English guide to the terms you'll encounter.

A-E

Argon Gas
An inert gas used to fill the space between panes of insulated glass. Denser than air, it improves thermal performance by reducing heat transfer.
Awning Window
A window hinged at the top that swings outward from the bottom. Good for ventilation during light rain.
Bay Window
A window assembly that projects outward from the wall, typically with three panels at angles (usually 30° or 45°).
Bow Window
Similar to a bay window but with 4-6 panels arranged in a gentle curve rather than at angles.
Casement Window
A window hinged on the side that swings outward, operated by a crank mechanism.
Double-Hung Window
A window with two sashes that both slide vertically. Both sashes can typically tilt inward for cleaning.
Double-Pane / Dual-Pane
Glass unit with two panes separated by a sealed air space. Standard for energy-efficient windows.
ENERGY STAR
Government certification program identifying energy-efficient products. ENERGY STAR windows meet specific performance criteria for your climate zone.
ER (Energy Rating)
Canadian rating system measuring overall window energy performance. Higher numbers are better.

F-L

Fixed Window
A window that doesn't open. Also called a picture window. Maximum light, no ventilation.
Frame
The main structure of the window that holds the glass and sash. Made of vinyl, wood, fiberglass, or aluminum.
Glazing
The glass portion of the window. Can refer to the glass itself or the process of installing glass.
Grilles / Grids
Decorative bars that divide window glass into smaller panes. Can be between glass, on surface, or true divided lites.
IGU (Insulated Glass Unit)
A sealed unit of two or more glass panes with air or gas between them. The "sealed unit" in your window.
Low-E (Low-Emissivity)
A microscopically thin coating on glass that reflects heat while allowing light through. Essential for energy efficiency.

M-S

Mullion
A vertical or horizontal bar dividing window units. Unlike grilles, mullions are structural.
R-Value
Measures resistance to heat flow. Higher numbers mean better insulation. (Inverse of U-factor.)
Sash
The frame that holds the glass and moves within the main window frame.
Sealed Unit
See IGU. The glass unit containing two or more panes sealed together.
SHGC (Solar Heat Gain Coefficient)
Measures how much solar heat passes through glass. Lower numbers mean less heat gain (good for south-facing windows in summer).
Single-Hung Window
Similar to double-hung but only the bottom sash moves; top sash is fixed.
Spacer
Material separating the panes in an IGU. "Warm-edge" spacers reduce condensation and improve efficiency.

T-Z

Tempered Glass
Safety glass that's heat-treated to be 4-5x stronger than regular glass. Breaks into small, less dangerous pieces. Required in certain locations.
Thermal Break
An insulating barrier within a frame (usually aluminum) that prevents heat transfer through the frame material.
Triple-Pane
Glass unit with three panes for maximum insulation. Recommended for Ottawa's extreme climate.
U-Factor
Measures heat transfer through the window. Lower numbers mean better insulation. Key energy performance metric.
Weatherstripping
Material around the sash that seals against air and water infiltration when the window is closed.

Have Questions?

Our team is happy to explain any term or help you understand your options.