Tip to Reduce Air Leaks Between Window Sash

Attaching window latch to window sash.

Older double hung window sash often rattle and allow cold air in where the two window sash meet. To prevent this from happening, install two window latches on each window, rather than just one, to pull the two sashes firmly together.

Space each window latch about one-third in from the sides of the window frame, or center each latch over a window pane.

Watch this video to find out more.

Further Information

Joe Truini: If your home has double hung windows, you might be familiar with this sound. It’s the sound of an ill-fitting, rattling sash. Now even with the sash lock engaged, you can still sometimes get rattling. And that’s the sound of you wasting money because heated air and cooled air is escaping.

So the solution is to replace the sash lock. Go to the store and get a new sash lock but get two. We are going to replace one sash lock with two. I’ll show you how that works. I did that on this window earlier.

First, I removed the old sash lock—and I’ll come back later and paint this and fill the holes—then I installed the new sash locks to either side about a third of the way in. Or in this case, I centered them on the glass pane on either side.

And now when you engage two locks, you’re locking the sash together in two different places and it’s no rattle at all. And you’re saving money year around.


  1. We have Double Anderson Double Hung Window fairly new about 11 years old cold air seeps through where the windows lock. What do you suggest is it the Window Locks or the Weather Strip?


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