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The Architectural Products Company

What Are the Pieces & Parts of a Window?

The average homeowner usually isn’t well-versed in window lingo, but the experts at APCO can piece together what homeowners mean when they talk about parts of a window. Still, have you ever wondered what a specific part or piece of your window is actually called? After all, “thingy” is hardly a technical term. And, what is a window jamb, anyway? We thought it might be helpful to break down the anatomy of a window and help you gain a better understanding of window terminology—especially if you’re thinking about replacing your windows any time soon!


For starters, be aware that the terms used for windows vary from manufacturer to manufacturer. This is often influenced by window type, the professional handling it, and even your country or region. We’ll try to use the most widely accepted/common terms here to make things less confusing.

What Kinds of Glass Pane Are Common?

The part most folks call the “window” is the glass component specifically, or the “pane.” Panes vary according to the window type, including double or triple panes (IGUs), decorative panes, etc.

What Makes Up the Window Frame?

Essentially the “house” of the glass pane, the frame provides support and the housing for your panes of glass. The frame, as a whole, is also responsible for the window’s functionality, providing the ability to open your window when applicable. Frames come in many different materials, including wood, vinyl, steel, and more. The frame itself is made of multiple parts, including:

  • The sill: The sill is the horizontal bottom of your frame.
  • The jambs: Jambs are the sides of your frame and, in most window types, this is where tracks or other mechanisms are housed to allow the opening of your window.
  • Head or header: The head/header is the opposite of the sill—located at the top horizontally.
  • The window apron: The apron is the decorative piece located under the sill of your window.

What is a Window Sash?

These are the “movable parts” of a window that provide the function of opening and closing. In most cases, there are two sashes—the upper sash, which is generally meant to be immobile, and the lower sash, which opens and closes. Sashes can be independent of the frame, but more often than not, “sash” is used as a term for the sum of a window’s parts, incorporating the frame and included mechanisms to create the sash.

What Does the Sash Lock Do?

The sash lock is the mechanism that locks or unlocks your window for the purpose of opening/closing. This part also reduces window shuddering, so if your window is rattling in the wind, the lock is often the part at fault!

What Is a Window Rail?

The rail is the place where your upper sash and lower sash make contact. This is the horizontal piece that “divides” your window. It’s also the piece that holds your window lock (sash lock). There is an upper and lower rail, corresponding with the sash it is attached to.

What Does a Lift Do?

The lift is a handle used to open or close your window. These can be small, decorative fixtures, or simply an indention in the rail design.

There are some other small window parts, of course, and while the information above is applicable to most window types, some styles such as casement windows have additional parts that support their unique design. For the most part, though, this should give you a solid understanding of the most common parts of your windows!


APCO is driven to bring you the best products and the best installation service possible. We offer high-quality window installation and service throughout the following cities and their surrounding areas: Bexley, Columbus, Dublin, Gahanna, Grove City, Lewis Center, Pickerington, Powell, Reynoldsburg, Upper Arlington, and Westerville.

“We were pleased with the overall execution of the planning and installation involved in this operation. You have a first-class work force. We thank you for your outstanding service.” – Cliff from Groveport

For a FREE window installation quote or to schedule service, contact us today »

* A minimum purchase is required. The discount applies to the retail list price and is not available on all products. Valid for a limited time and only for homeowner replacement customers who purchase APCO products for their residence and have them installed by APCO via the same contract. Not valid with any other offer or promotion. Repairs/handyman service, repairs to existing products including parts, and James Hardie and Mavin products excluded. Prior sales excluded. Other restrictions may apply. Loans provided by GreenSky (1797 Northeast Expressway NE Suite 100 Atlanta, GA 30329) on approved credit, repayment terms vary from 24 to 132 months. 16.93% fixed APR, effective as of July 1st, 2014, subject to change. Interest is billed during the promotional period, but all interest is waived if the purchase amount is paid in full within 12 months. There are no required minimum monthly payments during the promotional period.
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