How-to
How to Winterize Windows and Stop Drafts
🇩🇪 Diesen Artikel auf Deutsch lesenFind drafts with a candle or incense stick, then seal moving parts with weatherstripping and fixed gaps with caulk. For extra insulation, add clear shrink film or cellular shades. Together these can make rooms noticeably warmer and lower heating costs, for under $50 per window.
Air leaks around windows let warm air out and cold air in. You don't need new windows to fix most drafts — a few inexpensive materials make a big difference.
Step by step
- Find the drafts
On a windy day, move a lit incense stick slowly around the window frame, sash and trim. Where the smoke flutters, air is leaking.
- Clean the surfaces
Weatherstripping and caulk stick only to clean, dry surfaces. Wipe away dust and old flaking caulk.
- Weatherstrip moving parts
Apply V-strip or foam tape where the sash meets the frame. Close the window to check it seals without being hard to open.
- Caulk fixed gaps
Run a bead of caulk along gaps between the window trim and the wall, smooth it with a wet finger and let it cure.
- Add shrink film
Apply double-sided tape around the inside of the frame, stretch the film over it and shrink it tight with a hair dryer.
- Use window coverings
Close heavy curtains or cellular shades at night and open them on sunny days to let in solar heat.
Choosing the right material
| Gap | Material |
|---|---|
| Between the sash and frame (moving parts) | V-strip, foam tape or silicone bulb weatherstripping |
| Between frame and wall trim (fixed) | Paintable acrylic caulk indoors, exterior-grade caulk outside |
| Single-pane glass | Shrink film kits or storm windows |
| Large gaps around the frame inside the wall | Low-expansion window and door foam |
What it saves
Sealing air leaks throughout a home is one of the most cost-effective energy upgrades. Estimate your heating costs to see what even a 5–10% reduction is worth:
Home Heating Cost CalculatorEstimate your yearly and monthly heating billTry the calculator →Frequently asked questions
Will sealing windows cause condensation?
A tighter home holds more moisture. Use bathroom and kitchen exhaust fans and keep indoor humidity around 30–50%.
When should I replace windows instead?
If frames are rotten, glass is single-pane and drafts remain after sealing, or double-pane seals have failed, replacement may be worth it — but it pays back slowly.