Drafty windows letting in cold air
easy 30–90 min
Tools: incense stick or lit candle, utility knife, caulk gun, screwdriver, cloth · Materials: self-adhesive foam tape or V-strip weatherstripping, paintable interior caulk, exterior sealant, window insulation film kit for winter, rope caulk
Steps
- On a windy day, run a candle around the window: a draft at the sash edges means worn weatherstripping or a loose lock; at the frame, the caulk; at the meeting rail, sashes that are not pulling tight.
- Tighten or replace the lock so it pulls the two sashes together; a lock that closes without resistance is doing nothing for drafts.
- Pull off flattened weatherstripping, clean the surface, and press on new foam or V-strip; V-strip lasts longer on sashes that slide.
- Caulk the inside trim-to-wall joint with paintable caulk and the outside frame joint with exterior sealant, leaving the weep holes at the bottom clear.
- For winter, fit shrink film across the whole window or press rope caulk into the sash gaps; both come off cleanly in spring.
- Hang a heavy curtain or a cellular blind and close it at night — it is the cheapest insulation a leaky window will ever get.
Stop and call a pro if
- the glass is foggy between the panes — the sealed unit has failed and only replacement fixes that
- the frame is rotten, warped or the window will not close fully
- drafts come from the wall around the window, not the window itself — insulation is missing in the cavity
What a pro does that you can't
A window contractor replaces a fogged glass unit or the balances so the sash seals, and replaces a frame that is past sealing with a properly flashed unit; a handyman can do a whole house of weatherstripping in a day.
DIY cost: $10–40 in weatherstripping and caulk; $15–30 for a film kit