Stop drafts around windows
A draft doesn't always mean you need new windows. Cold air often gets in through worn weatherstripping or cracked caulk around the frame, and both are inexpensive to fix. Plan on about half an hour and less than $25 per window. On a windy day, a stick of incense or a damp hand run around the frame will show you exactly where the air is coming in.
Two kinds of gaps
Air gets past a window in two ways. Moving parts, where the sashes slide and meet, leak because there's a gap to allow movement; weatherstripping seals those. Fixed gaps, like where the frame meets the wall, leak because old caulk has cracked; fresh caulk seals those. Knowing which is which tells you what to buy.
Check inside too. The trim around the window on the inside wall often has gaps behind it, and a bead of paintable caulk there stops more cold air than you'd expect.
Where drafts come from
The strips that seal moving parts compress and crack over time.
The seal between the window frame and the wall dries out.
On double-hung windows, the two sashes need to be locked to seal together.
Fogging between double panes means the seal failed, which lowers insulation.
| Where you feel it | Best fix |
|---|---|
| Along the sides of a sliding or double-hung sash | V-strip weatherstripping in the channels |
| Where the two sashes meet in the middle | Lock the window. Add foam or a brush strip if it's still leaky. |
| Along the bottom of the sash | Foam tape on the bottom edge of the sash |
| Around the trim, inside the room | Paintable latex caulk along the trim edges |
| Where the outside trim meets the siding | Exterior caulk, leaving the weep holes open |
| A window you never open in winter | A shrink-film insulation kit for the season |
| Fog or moisture between the panes | Not a draft. The glass seal failed, so the glass unit needs replacing. |
Seal the gaps
- Find the leaksOn a windy day, slowly move a lit incense stick or a strip of tissue around the window edges. Where the smoke wavers or the paper flutters, air is getting through.
- Clean the surfacesWipe where the weatherstripping will go with rubbing alcohol. Adhesive won't stick to dust.
- Weatherstrip the moving partsApply V-strip along the sides of the sash channels and foam where the sashes meet or close. Test that the window still opens.
- Caulk the fixed gapsScrape out old, cracked caulk around the outside trim and run a fresh bead of exterior caulk.
- Use the lock, then retestOn double-hung windows, the lock pulls the two sashes together, so keep them locked in winter. Repeat the incense or tissue test; smoke that stays steady means the gap is sealed.
Watch it done
- Incense smoke stays steady around the window edges
- Tissue doesn't flutter along the gaps
- The window still opens and closes
- The lock pulls the sashes snugly together
Still drafty? Check outlets and baseboards on outside walls too.
If the room still feels cold
Check the outlets and baseboards on outside walls too. Air comes in around them more than people expect.
For a temporary window draft fix, shrink-film insulation kits add a clear layer of trapped air for a season.
Heavy curtains or cellular shades closed at night help a lot with cold glass. It's not a draft; single-pane glass itself just loses heat fast.
What a pro typically charges (a rough estimate; prices vary by area): Professional window sealing typically runs $100–$400 depending on the number of windows.
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