Symptoms
- Visible gaps, flattening, or tears in the foam or vinyl seal
- Draft felt along the sash even when locked
- Old weatherstripping crumbling when touched
- Higher energy bills in winter or summer
Likely causes
- CommonAge and compression over years of useFoam and rubber seals lose their spring back and compress permanently.
- CommonSun and temperature exposureUV and heat make weatherstripping brittle and prone to cracking.
- PossiblePhysical wear from repeated opening and closingHigh-use windows wear out their seals faster.
- Less commonWrong weatherstripping type for the gap size originally installedA mismatched seal never fully closes the gap.
What to do
- Open the window and examine the weatherstripping along the sash and frame for gaps, flattening, or damage.
- Measure the gap width and depth to choose the right weatherstripping type: V-strip, foam tape, or felt.
- Peel or pry off all the old weatherstripping, cleaning any adhesive residue with mild solvent.
- Cut the new weatherstripping to length for each side of the sash.
- Press self-adhesive weatherstripping firmly into place, or tack felt/V-strip per its mounting style.
- Close the window and check that it still opens, closes, and locks smoothly with the new seal in place.
- Feel around the edges on a windy day or with a hand near the seam to confirm the draft is gone.
Tools and parts
- Utility knife
- Scissors
- Tape measure
Self-adhesive foam weatherstrippingSearch: “window weatherstripping foam tape”
V-strip weatherstrippingSearch: “V-strip window weatherstripping”
When to call a pro
Call a handyman if you have many windows to do and want it done in one visit, or if the sash channel itself needs repair before weatherstripping will seat properly.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.