Best weatherstripping for old wood windows?

For old wood windows, you've got a few solid options depending on what you're dealing with. Felt weatherstripping is cheap and easy to install - you just peel and stick it around the frame - but honestly it wears out pretty quick, maybe a year or two before it gets compressed and stops sealing properly. Rubber or vinyl weatherstripping lasts way longer, usually five to ten years, and it handles temperature swings better without getting brittle. If you're working with windows that have seen some years, I'd lean toward the rubber kind since old wood can warp a little seasonally and rubber's more forgiving than felt about minor gaps.

The installation part is straightforward. Clean out all the old weatherstripping first, get the groove or frame surface really clean and dry so the adhesive sticks properly. Measure twice and cut your strips to fit snugly around the top, sides, and bottom of the sash or frame. Press firmly as you go, especially at the corners and where pieces meet. You don't want it so tight that the window binds up - test the operation after you're done and make sure it opens and closes smoothly.

One thing I've learned from dealing with old places during camping trips (staying in cabins and such) is that sometimes the wood's a bit soft or rotted in spots. If that's the case with your windows, you might need to do a little prep work first, like sanding down any rough areas or even replacing a small section of rot. Also consider whether your windows are rope-and-pulley style or just frame-and-sash - the actual application's basically the same, but knowing what you're working with helps you pick the right thickness and width of weatherstripping. V-strip weatherstripping is another option that works well in channels if your windows are that type.