How To Replace the Sash Lock on a Vinyl Window

Sash locks keep windows closed and intruders out. They can also improve your home’s energy efficiency by aligning the sashes and making a tight seal. 

If one of your windows’ sash locks is broken or missing, fixing the problem is relatively straightforward and you can tackle the job yourself with minimal tools and time. This Old House general contractor, Tom Silva, demonstrates how to remove and replace an old sash lock on a vinyl window. For more general sash window repairs, check out our guide to repairing a sash window. You may also want to check to see if your sash cords need replacing.

How Sash Locks Work

Sash locks consist of a locking mechanism and a keeper. When the lock is engaged, it pushes the bottom sash down and the top one up while also pulling the two together. This tightens the window at the meeting rail for a solid seal.

Consider replacing sash locks that are difficult to engage or disengage. A broken sash lock may also be the culprit behind a pesky draft or air leak around the window. 

Sourcing Replacement Parts

To find replacement sash locks, you’ll need to know your window’s manufacturer and model number. 

Look for a sticker with the manufacturer’s information on the window jamb and sash edge. If you can’t find any identifying marks, send photos, sketches, and information about the window’s type and age to a window parts dealer. They’ll identify what sash locks you need, and they might be able to sell you an exact match, even if you’re dealing with an obscure or discontinued window model.

Tools and Materials Needed

Once you’ve got the replacement sash locks from your dealer, it’s time to gather these tools and materials for the installation:

• Drill bit (matching the rivet size)
• Drill/driver
• Pop rivet gun
• Pop rivets (matching the size of the original rivets)
• Replacement sash locks
• Work gloves

The Replacement Process

Replacing sash locks is a relatively simple process that takes about 10 to 15 minutes per window.

Remove the Old Sash Lock

Sash locks attach to your window using specialized rivets. To remove the lock, choose a drill bit that matches the rivets’ size, and carefully drill each rivet out so you don’t accidentally break the frame or glass. You can then lift the old mechanism off the window.

Prepare the New Sash Lock

Before you put the new sash lock on, do one more comparison to make sure it’s the proper fit for your window. In particular, you want to check that the rabbet (the part that fits over the window profile) matches your window. Test-fit the new lock without securing it.

Install the New Sash Lock

If everything checks, position the new sash lock in place in your window. Put a pop rivet into your rivet gun, place the rivet over one of the existing holes, and squeeze the gun to secure it in place. Repeat the process for the other rivets.

You may need to replace the keeper along with the locking mechanism. It also attaches with rivets, so you can use a drill and rivet gun to secure it to the other sash.

When the new lock is on, test it to make sure it operates smoothly and engages properly with the keeper.

Repeat the process for any other windows that need sash lock replacement. The first one is the hardest, and you’ll become more efficient with each window.

Maintaining Your New Sash Locks

After replacing your sash locks, proper maintenance can help them function at their best. Use a dry lubricant as necessary to keep them operating smoothly. When you wash your windows, make sure the rivets keeping the lock and keeper in place are secure and corrosion-free.