Understanding Parts of a Window

Window Parts and Components

New or updated windows can provide your home with added curb appeal and better energy efficiency. What most homeowners don’t realize is the number of parts that make up a window and the role each component plays in the window’s overall function. Understanding each piece and being able to pinpoint them on your window can help when it comes time to plan your next window replacement project or window repair.

While there are a lot of window parts out there, it’s easiest to separate them into three main groups—frame parts, glass parts, and additional parts. Most parts will be standard in some way, regardless of window type, but more specialty windows might feature unique components.

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Window Frame Parts Diagram

A window frame supports the window and its glass panes. All the parts of a window frame work together to hold the window unit and window glass together.

• Sill: The horizontal part forming the frame’s base.
• Jambs: The vertical parts that form the frame’s sides and secures the panes.
• Head: The horizontal part forming the frame’s top.
• Sashes: Comprised of the horizontal and vertical parts of the frame that secure the glass. Window sashes are often used to open windows.
• Jamb liner: A strip on the frame’s sides that provides a snug fit for the sash.
• Grids (Grilles or Muntins): Decorative pieces that divide the panes, providing added stability.
• Stiles: The vertical part of a sash, parallel to the jambs.
• Rail: The horizontal parts of a sash, comprised of a lower, check (where the bottom part of the upper sash and the upper part of the lower sash come in contact), and upper rail..
• Locks: These mechanisms serve to secure the window from outside intrusion, as well as offer added stability to reduce rattling.

Window Glass Parts

• Panes: The central, glass part of a window in which the entire structure is attached. Modern windows can include double- or triple-pane options for added protection and/or noise reduction.
• Spacers: Situated at the base and top of the frame to provide distance between the panes. Double and triple panes require additional spacers.
• Argon Gas: This optional feature is included in many energy-efficient windows and is injected between the panes to offer added insulation and noise reduction.
• Apron: An optional trim that is placed below the stiles providing additional support and decoration.

Read our guide to window glass to understand glass types based on efficiency, design and utility.

Additional Parts

• Casing: Window casing is decorative molding or framing around a window used to conceal the space between the frame or jamb and wall.
• Hinges (casement windows): Since casement windows open outward, they require hinges to properly function. These components hold the sash to the frame from the outside.
• Lock Strikes (double hung windows): Double-hung window consist of upper and lower sashes that can be locked in the middle using a strike.
• Operator’s Arms (awning windows): The opening mechanism of awning windows that is placed at the sash’s base. Awning windows in basements often place this arm on the top instead
• Sash Pulls (slide windows): Part of the sash hardware that is used as a handle to open and/or close slide windows.
• Weatherstripping: A strip of resilient material that reduces air leaks and prevents water from entering the home by covering the joint between the sash and frame.
• Screen: Typically a metal, plastic, or fiberglass woven mesh that covers a window opening to block out insects but allow air and light in.

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How They Impact Window Costs

Not all windows are the same. Each window includes different required parts and may offer optional features. The window type, frame material, energy efficiency, and any custom upgrades all affect the total installation cost.

In general, the more complex or customized a window is, the more homeowners can expect to pay for installation.

Can They Be Replaced?

The good news is that most window parts can be replaced. Some repairs are simple and affordable, while others are more involved. For example, replacing a lock or weatherstripping is usually easier, and cheaper, than fixing rotted window jambs.

Rotted jambs can also point to bigger issues. The head, sill, or other window components may be damaged as well. That’s why it’s best to have a professional inspect your windows as soon as you notice signs of wear or damage.

Are Window Parts Covered in Warranties?

If your windows show signs of damage or wear, you may be able to reduce costs by using your window warranty. Coverage varies by manufacturer, but many warranties include key components such as frame, glass, and hardware.

Keep in mind that different window parts may be covered for different lengths of time. Before starting a repair or replacement project, review your warranty details or contact the manufacturer. They’ll let you know whether any costs can be offset.

Understanding how your windows are built helps you plan repairs and replacements with confidence. Modernize can connect you with trusted local contractors to help you take the next step.

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