Replacement Window Glossary Of Terms

When you’re looking to replace any of the windows within your home then you’re likely to be bombarded with facts and terminology which is brand new to you, this can often be quite daunting and in some cases lead to a lot of confusion.

This replacement windows glossary guide is designed to provide you with a list of the most commonly used words, phrases and expressions in the world of window replacements. This will allow you to fully understand what potential window contractors are saying to you as well as better understanding what you need and why you need it.

Replacement Window Terms

Single Glazing – A replacement window which has a single pane of glass only.

Double Glazing – A replacement window which has a two panes of glass, usually separated by a gas filled space. Commonly the gas will be argon but krypton is being more commonly used in energy efficient windows.

Triple Glazing – A replacement window which has three panes of glass, each separated with a gas filled space. Triple glazed windows are used in many colder climates where comfort in the home is more important due to the extreme cold.

Head The uppermost part of the window which sits above the top of the frame, the head is usually decorative and available in many different styles and choices.

Jamb Jambs sit inside the window frame and form the main structural integrity of the window, they are often one of the first things to require replacement.

Frame The outermost part of the window which holds the glass and provides the main structural support. Frames can be made from any number of different materials including wood, metal, aluminum, vinyl and plastic.

Panes The glass which sits inside of the window frame allowing you to see through the window and allowing light in whilst still providing protection from the outside elements.

Sill Similar to the “window head” but the sill sits at the lowest part of the window underneath the bottom of the frame. Often used for placing objects on.

Muntin Bars Used to be used to provide separation and hold multiple panes of glass in place which made up a single window. Nowadays though they are more for decorative purposes and laid upon a single pane of glass to give the illusion that the window is made from several separate panes, rather than joining multiple panes together.

Sash The movable panel within the single or double hung window. Sashes will hold or house one or more panes of glass.

Single Hung Window A window with only a single sash that moves in either an up and down or tilting motion.

Double Hung Window A window with two sashes, both of which move in either a tilting or up and down motion.

Bow Windows A window setup similar to bay windows but these are installed in a curved configuration forming a semi-circular layout. Usually constructed using multiple single casement windows.

Bay Windows A window setup similar to bow window but these are usually installed in an angled configuration with 1 casement window to the right, 1 to the left and 1 or multiple is the center.

Awning Windows A window which swings outwards from the frame, the hinges are usually fixed just below the window head.

Fixed Frame Windows As the name suggests these have a single fixed frame with no opening portion to the window.

Sliding Windows Windows which are able to slide open from one side to the other on a set of rails. A single hung sliding window has only one movable sash, a double has two movable sashes and a multiple hung sliding window contains more than two sliding sashes.

Energy Efficiency Terms

U-Factor – A measure of the rate of heat transfer. Tells you how well a window insulates.

Window R Value – The window R value is a rating of thermal resistance, or in other words the window’s ability to hold in heat through installation.

Solar Heat Gain Coefficient (SHGC) – A measure of the amount of solar energy transmitted through the window.

Visible Transmittance (VT) – A measure of the amount of light allowed through by the window.

Air Leakage (AL) – A measure of the rate at which air passes through the window joints and gaps.

Condensation Resistance – A measure of the window’s resistance to water build-up