Doors & windows

Stop drafts around windows

Sit near the window on a cold night and you can feel it: a thin stream of cold air. Drafty windows make rooms uncomfortable and heating bills higher, but you rarely need new windows. Weatherstripping and caulk fix most leaks for the price of a pizza.

Written and reviewed by Grab the Hammer Team · Updated Sep 2026
Double-hung window showing air leaks between sashes, along sash edges and around the trim
Where drafty windows leak: between the sashes (1) and along the sash edges (2), which need weatherstripping, and around the trim (3), which needs caulk.

What's actually going on

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.

Why it happens

Worn weatherstripping

The strips that seal moving parts compress and crack over time.

Cracked caulk

The seal between the window frame and the wall dries out.

Sashes that don't meet

On double-hung windows, the two sashes need to be locked to seal together.

Failed glass seals

Fogging between double panes means the seal failed, which lowers insulation.

Before you startDon't caulk over weep holes on the outside bottom of the frame. They let water drain out.

Let's fix it

0 of 5 done
  1. 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.
    Lit incense stick moved along a window edge, its smoke wavering where cold air leaks in
  2. Clean the surfacesWipe where the weatherstripping will go with rubbing alcohol. Adhesive won't stick to dust.
    Rubbing alcohol on a rag wiping the window sash channel so weatherstripping adhesive sticks
  3. 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.
    V-strip weatherstripping pressed into the side channel of a window sash, and foam where the sashes meet
  4. Caulk the fixed gapsScrape out old, cracked caulk around the outside trim and run a fresh bead of exterior caulk.
    Fresh exterior caulk bead run where the window trim meets the siding
  5. Use the lockOn double-hung windows, the lock pulls the two sashes together. Keep windows locked in winter for a tighter seal.
    Window sash lock turned closed, pulling the two sashes tight together

Still not fixed?

Still cold after sealing? Check the outlets and baseboards on exterior walls too; they leak more air than people expect.

For a temporary window draft fix, shrink-film insulation kits add a clear layer of trapped air for a season.

Tip from experienceFor a quick seasonal fix on a window you never open, clear shrink-film window insulation kits are cheap and surprisingly effective.
Time to call a pro if you seeFogging between double panes (a failed seal), soft or rotten wood, or windows that won't open at all.

What a pro charges: Professional window sealing typically runs $100–$400 depending on the number of windows.

Common questions

How do I tell if my windows are drafty?

On a windy day, move a lit incense stick or strip of tissue along the edges. Wavering smoke or fluttering paper means a leak.

Is it worth replacing drafty windows?

Often not right away. Weatherstripping and caulk fix most drafts for a small fraction of the cost.

What's a quick temporary fix for a drafty window?

Rope caulk pressed into gaps or a shrink-film insulation kit works for a season and peels off in spring.

About the authors

Grab the Hammer Team

We're a small team of home repair writers and editors who test our advice against manufacturer instructions and common code requirements. Our goal is simple: help you fix what you safely can, and know when to call in a pro.

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