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Window, Door, & Siding Terms in the Chicagoland Area

Air Infiltration Rate
The amount of air leaking in and out of a building through cracks in walls, windows, and doors (the lower, the better). Usually expressed as cfm per square foot of window area.

The process that provides a hard, durable oxide film on the surface of aluminum, by electrolytic action.

A mechanical device used in double hung windows to counterbalance the weight of the sash during opening and closing. These will vary between manufactures.

A molding or stop placed around a window frame to hold glass in place by pressure.

Casement Window
A window in which the operating vents move out from the master frame. Each vent is hinged on the right or left side depending on the application.

When the air inside an enclosure is warmer than the air outside the enclosure, the moisture vapor in the interior air will condense, creating small water droplets at the intersection of dissimilar materials (aluminum and gaskets).

Fusion Weld
Method to join the vinyl frame and/or sash members by heating the cut ends, squeezing them together, and allowing the assembly to cool.

A rubber or plastic pliable material used to separate glass and vinyl.

The process of installing glass or panels into the sash or frame of the window.

Hopper Window
Two pieces of glass spaced apart and hermetically sealed to form a unit with an air space between. Heat transmission through this type of glass may be as low as half that without such an air space.

A design feature which enables sash to engage one another when closed.

The vertical member of a window frame.

A hardware device into which a window locking latch engages for security.

Laminated Glass
Two or more lites of glass bonded together with a plastic inner layer. A typical application is a car’s windshield.

Low E Glass
A transparent coating applied to a glass surface to separate long wave (heat) energy and short wave (light) energy. The long wave is reflected back to the heat source. The short wave is allowed to pass through the coating.

Meeting Rail
The part of a hung window where the two sash meet and create a weather barrier.
An extrusion that joins windows.

Pivot Bar
Hardware in a double hung window to connect the balancer with the operating sash.

The lower horizontal member of a window frame.
Single Strength Glass
(SSB) 3/32" thickness.
Sliding Glass Door
A door in which the operating panel slides sideways within the master frame. Each operating panel has rollers to permit easy operation. Also called a patio door. Usually used in applications where passage to exterior patios is required, while providing weather resistance and security.
Sliding Window
A window in which the operating sash slide sideways within the master frame. Each operating sash has glides or rollers to permit easy operation.
Tempered Glass
Glass that has first been cut to size, then heated to a very high temperature and then rapidly brought back to room temperature. It will withstand severe punishment from a blunt object; however, any pointed object will break the glass instantly and the glass will crumble into many, very small pieces. Typical applications include a car’s side and back windows, sliding glass doors, and entrance doors.

Thermal Break
An element of low conductivity (polyurethane) placed between elements of higher conductivity (aluminum) to reduce the flow of heat and cold.

Tilt Release
Hardware in a tilt hung window to hold the sash within the frame jambs and, if desired, release the operating sash to the tilt position for cleaning of the exterior glass and sash removal. Common release design options include finger buttons, slots for a common tool, hardware for special tools, or key operation.

U Value
A measurement of heat transmission. The U value of a window is measured by the number of BTU's that will pass through each square foot of area per degree of temperature difference from one side of the window to the other (the lower, the better). U value = the number 1 divided by the R value.

United Inches (UI)
The sum total of one window width and one window height expressed in inches.

Weep Hole
An opening in a window sill and/or sash rail to allow water to drain to the exterior.

Window Size
Always expressed as width first, then height.

Window Style
The description of the way a window operates, e.g., double hung, sliding, casement, etc.