Check caulking around windows/doors

Inspect the seals around exterior doors and windows for wear, gaps, and air leaks, then replace damaged weatherstripping to maintain energy efficiency.

Why it matters#

Worn weatherstripping lets conditioned air escape and outdoor air sneak in—accounting for up to 30% of heating and cooling energy loss according to the Department of Energy. Proper sealing improves comfort (no more drafts!), reduces energy bills by 5-20%, keeps out pests and moisture, and reduces outdoor noise.

What you'll need#

Tools#

• Flashlight
• Incense stick or candle (for draft testing)
• Dollar bill
• Tape measure
• Utility knife
• Scissors

Materials#

• Replacement weatherstripping (foam tape, V-strip, or door sweep—type varies by location)

Steps#

1. Conduct a Visual Inspection#

Examine weatherstripping around all exterior doors and windows. Look for obvious damage: cracks, tears, compression (flattened areas), gaps, peeling adhesive, or sections that have fallen off completely. Check where different materials meet—corners are common failure points.

2. Perform the Daylight Test#

On a sunny day, close doors and windows, then darken the room. Look around the edges—if you see light coming through the frame, air is getting through too. This works best for doors; for windows, look at all four sides of the sash.

3. Do the Dollar Bill Test#

Close a door or window on a dollar bill so it's half in, half out. Try to pull the bill out. If it slides out easily with no resistance, your weatherstripping isn't sealing properly and needs replacement. Repeat at multiple points around the door.

4. Use the Incense Test for Hidden Drafts#

On a cool, windy day, light an incense stick and slowly move it around door and window edges. Where smoke wavers, flickers, or gets sucked in a direction, you've found a draft. Mark these spots with painter's tape for repair.

5. Check Door Bottoms and Thresholds#

The gap under doors is a major source of drafts. Inspect the door sweep (the flexible strip at the bottom) for wear and proper contact with the threshold. With the door closed, you should not see daylight underneath.

6. Inspect Window-Specific Areas#

For double-hung windows, check where the upper and lower sashes meet (the meeting rail) and along the sides where sashes slide. For casement windows, check the entire perimeter where the sash meets the frame. Rattling windows indicate air leakage.

7. Replace Worn Weatherstripping#

Clean the surface thoroughly before applying new material. For doors, foam tape or rubber gaskets work well on the top and sides; use a door sweep for the bottom. For windows, V-strip (also called tension seal) works great for sliding surfaces. Cut pieces to length and apply firmly.

Pro tips#

• Different weatherstripping types suit different applications: foam tape is cheapest and easiest but least durable; V-strips (tension seals) are excellent for windows and door sides; door sweeps address under-door gaps; and rubber gaskets provide the best seal but may require nails.
• Before applying self-adhesive weatherstripping, clean the surface with rubbing alcohol for maximum adhesion.
• Check and tighten door hinges before installing new weatherstripping—a sagging door creates uneven gaps that even good weatherstripping can't fix.

Warnings#

• Don't seal windows shut with caulk or permanent adhesive—you need to be able to open them for ventilation and emergency egress.
• In very tight homes, some air exchange is actually necessary for indoor air quality. If you seal everything perfectly, consider whether you have adequate ventilation.

When to call a pro#

Weatherstripping is a DIY-friendly task, but consider calling a professional if you have significant gaps due to a warped door or window frame, if your doors or windows don't close properly, or if draft problems persist after replacing weatherstripping (could indicate window/door replacement is needed). An energy auditor with a blower door test can precisely locate all air leaks.