Anatomy of a Window: The Important Parts Homeowners Need to Know

If you’d like to quickly upgrade the beauty and livability of a home, new window installation is a great solution. Since many homeowners know next to nothing about the parts that make up a window, besides the frame and window panes, we have taken the time to share the details on the basic window components you should be familiar with before selecting new hardware.

If you are looking for new window styles for your home, here are the need-to-know parts of most windows.

The Head

Simply put, the head of a window is the horizontal member of the frame at the top of the unit. The head can be made from wood, fiberglass, aluminum or vinyl depending on the model in question. The head screws into the header of a rough window opening.

The Jambs

A window’s jambs are the two vertical members of the frame that connect the head to the sill. They’ll almost always be made from the same material as their matching heads and sills. Jamb liners attached to the jambs ensure that a window’s sashes have the appropriate fit.

The Sill

A sill is essentially the lower equivalent of the head. The sills on sliding windows will boast fixed tracks that allow for lateral movement. Most sills have a sloping surface to ensure that rain can easily drain away from the window.

The Sashes

The discrete movable parts of a window that include a sheet of glass and a frame of its own is called a sash. In single or double-hung windows, there are two sashes that slide against each other. Sashes ride on metal or vinyl tracks in a window frame’s jambs or its head and sill to facilitate movement.

The Rails

Rails are the horizontal members of sashes that hold the actual glass securely in place. A check rail is the portion of a double-hung window where the upper sash meets the lower sash. The lower rail of a lower sash usually has a lift or handle.


Panes are the flat pieces of tempered glass that provide a barrier between the inside of the house and the exterior. Many modern windows have two or three panes of glass that encapsulate layers of a noble gas like argon (don’t worry, it’s not dangerous!) to improve heat retention.


A grille is just a decorative arrangement of vertical and horizontal strips that divides a windowpane into multiple segments. Some manufacturers refer to grilles as muntins in their promotional literature. Grilles are often positioned in between multiple panes of glass to protect the latticework from physical damage.

The Interior Casing

High-quality windows typically feature a layer of additional molding around the exterior of the frame. This interior casing fills the space between the frame and the rough opening, making it easier to prevent drafts. It also improves the overall aesthetics of an installed window unit.

Getting the Most From New Windows

Finding a great deal on window repair or window replacement is far easier if you have a little window knowledge in your back pocket. Hopefully, this quick rundown of window parts and their definitions will help you to make smarter buying decisions.


Need New Windows for Your Home? Contact Schmidt Roofing for a Free Estimate Today!

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