Would larger wool pile help fill the gap of my crooked sash

Question

I noticed a significant draft coming from many of my home's older vinyl windows. Upon closer inspection, it seems that there are gaps in the pile weatherstripping, large enough where daylight is coming through. From the measurements and photos, it seems that the height is about 1/4", and the plastic track seems just slightly larger than 1/4" (9/32" perhaps?).

If you can see in the photo taken of the window, the gap between the window and the frame seems to vary, going from most narrow at the bottom and top to the widest near the middle. This is the case on multiple windows. I don't know if the windows were installed incorrectly, if they're just low quality, or if this is normal seasonal expansion/contraction due to the changing temperatures. The windows came with the house so I don't know how old, what brand, who installed, etc.

My question is, can I / should I get a taller pile, 11/32", to fill the larger gap near the middle of the window, or will it be too thick on the top and bottom and cause binding?

Thanks for the help!

Tom · Accepted Answer

I don't think getting a taller wool pile will fix things for you since, like you said, it would be too thick in the areas where the sash is closer to the frame. It would be a temporary fix at best, and it would probably make the window harder to open and close at worst.

I think finding a way to re-square your sashes should be your first priority. There's a good chance your windows are out of square due to age and the house settling, but it could be any of the other possibilities you mentioned, like improper installation or even damage that you can't see. It's tough to say from this vantage.

It could be a simple matter of uninstalling the sashes and installing them again. I would try that first. If that fails, look for any damaged hardware, especially the pivot bars and pivot shoes. If they aren't seated properly then it could account for that slant.

If everything appears to be installed and functioning properly, then the issue is probably with the frame. At that point I would get the help of a local professional to look over your window.