We know there are a lot of confusing terms and language associated with windows and doors. We hope this glossary makes shopping for a window or door easier and more efficient. If you have questions about any information not included in this glossary, feel free to contact us or your local distributor.

Argon Gas

Argon is a safe, odorless, colorless, non-toxic, non-flammable inert gas commonly used in place of air between the glass panes of an insulated Low-E glass unit.


Emax® Glass

A transparent coating applied to a glass surface to separate heat energy and light energy. The radiant light that comes through the window is reflected back to the outside in summer and inside in the winter. The light is allowed to pass through the coating.


Emax Plus® Glass

Emax® Plus Glass has a safe, odorless, colorless, non-toxic, non-flammable gas that is used in place of air between the glass panes of an insulated unit. It adds additional insulating value to the glass unit.


Insulating Glass (IG)

Insulating glass is made up of 2-lites (panes) of glass separated by a spacer around the perimeter, with a sealant applied to bond the plates to the spacer to form a sealed unit.


Laminated Glass

Laminated glass is used in most blast-resistant and hurricane-resistant glazing. This type of glass is composed of a glass “sandwich” of two bonded lites of glass with a plastic interlayer between them. Laminated glass may fracture, but fragments remain in place inside the window if properly glazed.


Low-E Glass

Low- E, or low-emissivity, glass is used to reduce the amount of infrared and ultraviolet light that comes through your window without compromising the amount of light that enters your home.


Obscure Glass

Mainly used for decoration, diffusion or privacy. The pattern is rolled into the hot glass during glass manufacturing.


Tempered Glass

Tempered glass is treated by heat or chemicals for added strength. If tempered glass is broken, it disintegrates into small, circular fragments instead of sharp, jagged pieces for easy cleanup. For this reason, tempered glass is commonly used in swinging doors, sliding patio doors and storefront windows.

Awning Window

A window unit in which the bottom of the sash swings outward and up.


Bay Window

A combination of three windows (casement, double hung or picture windows) usually made up of a large center unit and two flanking units at 30, 45 or 90 degree angles to the wall.


Bow Window

A combination of four or more window units in a radial or bow formation at a 10 or 15 degree angle.


Casement Window

A window unit in which the single sash cranks outward, to the right or to the left.


Cottage Window

A double hung window in which the upper sash is shorter in height than the lower sash.


Double Hung Window

A window unit that has two operable sashes which move vertically in the frame.


Garden Window

A window that extends outward and sits like a box. All surfaces of the window are glass and typically used as a setting for growing indoor plants.


Geometric Windows

Windows that are made in architectural shapes such as trapezoids, ellipses, half rounds, circles, etc.


Hung Window

A window in which the operating sashes move up and down within the master frame. The weight of each operating sash is counterbalanced with balances for easy operation.


Oriel Window

A double-hung window in which the lower sash is shorter than the upper sash.


Picture Window

Non-venting or non-operable window. Also known as a fixed window.


Single Hung Window

A type of window in which the top sash is fixed or inoperable.

Sliding Patio Door

A door in which the operating panel slides sideways within the master frame. Each operating panel has rollers to permit easy operation. Usually used in applications where passage to exterior patios is required, while providing weather resistance and security. Not to be confused with mall or entrance sliding doors which provide security, but little or no weather resistance.


A mechanical device, normally spring loaded, used in hung windows to counterbalance the weight of the sash during opening and closing. Three types used in vinyl windows are spiral, block & tackle and constant force.



A handle or grip that is applied or is an integral part of the bottom rail of the lower sash (top rail of upper sash) of a double hung window to make it easier to raise or lower the sash.



A wood, vinyl, metal (or a combination of the three) part used to structurally join two window or door units.



The opposite part of the cam lock that connects the two parts when the window is locked.



A separately framed piece, or pane, of glass in windows and doors



The vertical and horizontal part of the window that holds the glass frame. May or may not be movable.

  • Rail: The horizontal piece of the sash.


Unison Lock

A casement locking system which secures the window at two locking points by operation of one handle.