Window & Door Terminology

Everything you ever needed to know & more!

We get it. People love to explore information online before setting foot in a store to shop. The internet is full of resources and reviews for windows, product education on doors, and so much more. Here’s our helpful guide to understanding our industry’s terminology. We hope it helps empower you to become a little bit of a “fenestration expert” yourself.

Have a question?

Whether it’s product education or service and repair, we’re here to help!

From A to … X

From Argon to XO, we’ve got you covered with this quick reference glossary!

Whether you are buying windows or calling in to discuss a service or repair need, it’s always good to know what it is you are trying to describe.  Marvin Windows and Doors helped us out by compiling this easy reference list. Here are some of the most common terms:

A - M: Click for Details

A colorless, odorless gas used to fill the airspace between insulated glass. Increases the insulating performance of the glass.

A block and tackle system used in the vinyl jambliner of double or single hung windows. Allows the sash to move up & down.

Part of the frame on a window located between the jamb and the brick molding, which forms a frame to support a storm window or screen.

A window hinged on either side, opens to the outside like a door.

The area where the bottom rail of the top sash and the top rail of the bottom sash meet when the window is closed.

Refers to a wood window that has parts, which are covered with aluminum or vinyl on the exterior of the frame and sash.

The measurement denoting the width and height of visible glass.

A window with two vertical sash, in a single frame which slide by each other for upper or lower ventilation.

Two or more pieces of glass separated by a spacer and hermetically sealed together with a primary seal of polyisobutylene and a secondary seal of polyurethane (dual seal), also referred to as a Thermopane or I.G. Glass.

Flat pieces of wood applied to the inside of the window jamb extending the width of the window to a wider wall size, extension jambs are flush with the inside finished wall allowing casing to be applied to the interior.

The vinyl vertical tracks on the sides of double and single hung windows, houses the balance tubes and clutch system assembly.

Two pieces of glass separated by a thin plastic film. Used in hazardous locations. Windshields, doorlites etc.

Low-E stands for low emissivity. Low-E glass reduces radiant heat transfer through the glass. The lower the emissivity, the lower the heat allowed to be radiated and the higher the reflection (re-radiation). 2-types, soft coat (vacuum or sputter coated) & hard coat (pyrolytic). You want a high r-value.

Horizontal and vertical bars, which may be within an insulated glass unit to form a grid or diamond pattern. May also be an actual part of the sash, which divides individual panes of glass.

N - X: Click for Details

The vinyl or aluminum fin of the exterior frame that is used for installing clad units.

A divider made of weatherstripping or wood, which separates the sash. Parting stops are commonly found at the head and side jamb of double hung windows and patio doors.

The measurement of thermal resistance of a given material, the higher the number the more resistance. Higher the better.

The cross or horizontal members of the framework of a sash or door panel.

The portion of a window which is separate from the frame and into which the glass is set, can either be stationary or operable. Consists of stiles, rails and glass.

A lever operated locking device, which holds a window shut by locking around a keeper. Located at the meeting rail on double hung and gliding windows or on the side jamb of casement windows.

The vertical members of the window frame.

The horizontal member forming the bottom of a window or exterior door frame, the lowest member of the frame of a structure, resting on the foundation and supporting the frame.

A window stacked above a window or door, can be either stationary or operable. Mulled to another window/door or separate.

Individual lites of single or insulated glass separated by muntin bars. Common in older double-hung windows.

The heat flow rate through a given material, the lower the number the less heat loss. Lower the better.

A strip of material, such as metal, plastic, vinyl or felt pile designed to seal between a sash and frame, preventing air and water infiltration.

The letters OX or XO identify the operation of window or door units as viewed from the exterior. The letter O stands for stationary while the letter X stands for operating.

Too many choices? Not sure where to start your search?

Featured Partners