Drafty Windows — How to Stop the Cold Air

Cold air seeping around windows makes your heating work overtime. Most drafts are easy to fix with basic weatherstripping and caulk.

Find the Drafts

The candle/lighter test: On a windy day, slowly move a lit candle around the window frame. Flickering indicates air movement.

The hand test: Feel around the edges with your hand — drafts are often obvious.

The paper test: Close the window on a piece of paper. If it slides out easily, the seal is poor.

Common Draft Sources

1. Worn Weatherstripping

The strips that seal the moving parts of the window wear out over time.

Fix: Replace with new weatherstripping ($5-15 per window)

• V-strip (bronze or plastic) for double-hung windows
• Foam tape for simpler applications
• Felt for inside tracks

2. Gaps in Caulk

The caulk sealing the window frame to the wall can crack and separate.

Fix: Remove old caulk, apply new exterior-grade caulk ($5-10)

• Use silicone or polyurethane for best durability
• Apply in temperatures above 40°F
• Smooth with a wet finger for a clean line

3. Single Pane Windows

Old single pane windows just aren’t very efficient.

Temporary fixes:

• Window insulation film ($20-40 for multiple windows)
• Thermal curtains
• Interior storm windows (acrylic panels)

Permanent fix: Window replacement (expensive but effective)

4. Gaps Under the Sill

Air can enter under the interior sill.

Fix: Remove the sill, add insulation behind it, reinstall, and caulk.

DIY Weatherization Steps

1. Clean the surfaces — caulk and weatherstripping won’t adhere to dirt
2. Remove old weatherstripping and caulk — start fresh
3. Apply new caulk around the frame exterior where it meets the wall
4. Apply weatherstripping to all moving parts
5. Consider window film for added insulation on older windows

When to Call a Pro

• Windows are severely damaged
• Frames are rotted
• You want full window replacement
• You’re not comfortable on a ladder for exterior caulking

The Bottom Line

Most drafty windows can be fixed with $20-50 in weatherstripping and caulk. It’s one of the best ROI home improvements — you’ll feel the difference immediately and see it on your energy bills.