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How to Replace Window Jamb Liners

Keep aging replacement windows operating smoothly

FH10OCT_BROWJA_01-2 egress window sizeFamily Handyman
What is a window jamb and what to do when you need to replace jamb liners. When sash lifts or cords on double-hung replacement windows break, the easiest fix may be to replace the jamb liners. Once you identify and locate the new parts, swapping the liners is simple.

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Locate a replacement window liner

Photo 1: Remove the sash

Push in on the jamb liner while you pull out on the top corner of the sash. Release the opposite side using the same technique. Then pivot the sash downward and tilt it sideways to remove it.

Photo 2: Pry out the jamb liner

Starting at the bottom, wedge a stiff putty knife into the crack between the jamb liner and the window stop. Pry the jamb liner flange out from under the stop. Then slide the putty knife upward to release the jamb liner.

Photo 3: Look for part numbers

Find the information you’ll need to order new jamb liners stamped on the metal balance cartridges.

Modern double-hung windows (the upper and lower window sashes slide up and down past each other) don’t use pulleys and sash weights to support the sash (the moving part of the window). Instead they have liners on each side that contain a spring assembly. If your sash won’t stay in the raised position, chances are that some part of the jamb liner hardware is broken. You might be able to spot a broken cord or other sign of problem by looking closely as you open and close the window. If you determine that the jamb liner mechanism is broken, you can fix it by replacing both jamb liners.

The first step is to find a source for the new jamb liners. The original manufacturer is the best source of replacement parts. If you don’t know what brand your window is and can’t find a label, search online (try “window parts”) for a window repair parts specialist that can help you identify the jamb liner and send you new ones. But you may have to remove the jamb liner first and send in a sliver of it. Another option is to scan or photocopy the end profile of the jamb liner and e-mail the image to the parts supplier. Temporarily reinstall the old jamb liner and sash to secure the house while you’re waiting for the new parts to arrive.

The photos show how to remove a common type of jamb liner on a Marvin window. Photo 3 shows where to find the information you’ll need to order a new Marvin jamb liner. Start by tilting out the sash (Photo 1). Then remove the jamb liner (Photo 2).

Required Tools for this window liner project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Putty knife

Required Materials for this window liner project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.

  • Replacement jamb liners