Draughtproof a casement window with self-adhesive strip
Fit self-adhesive foam or rubber strip around a casement window to stop draughts in one afternoon.
DW-01Check the weather and gather your kitPick a dry day above about 5°C — adhesive strip won't stick properly in the cold or damp. Lay out your strip, scissors, a cloth, sugar soap or methylated spirit, and a tape measure before you start.
1 each · Self-adhesive foam draught strip (5m roll)
DW-02Clean the frame rebate thoroughlyOpen the window and find the rebate — the ledge the opening sash presses against when shut. Wipe it with sugar soap or methylated spirit to remove grease, dust and any old strip residue, then dry it completely. The strip won't bond to a dirty or damp surface, so give it a few minutes to air dry.
DW-03Find where the draught actually gets inClose the window and run your hand around the frame feeling for cold air, or hold a lit match or lighter near the edges on a windy day and watch the flame flicker. This tells you which sides need strip most, and roughly how big the gap is.
DW-04Check the gap size before you buy the wrong stripClose the window on a strip of card or paper and try to pull it out. If it slides out easily, the gap is small and thin foam strip will do. If it grips hard or won't close properly with card in, you need a thicker foam or a rubber E- or P-profile strip instead.
DW-05Measure each side of the frameMeasure the length of the top, bottom, and both sides of the rebate separately, since window frames are rarely perfectly square. Add about 20mm extra to each measurement so you have a little spare to trim.
DW-06Cut the strip to lengthCut one length for each side using your measurements from the last step. Cut the corners at a 45° angle so the strip meets neatly rather than overlapping in a lump, which stops the window closing properly.
DW-07Stick the strip to the rebate, not the sashPeel back a short section of backing paper and press the strip onto the clean, dry rebate — the fixed frame, not the moving sash. Work slowly along each side, peeling the backing a little at a time and pressing the strip down firmly with your fingers as you go.
DW-08Fit the corners and finish each sideButt the mitred corners together as closely as you can without gaps. Press the whole length of strip down firmly once more, especially at the corners, so it's properly stuck before you close the window on it.
DW-09Test the window closes and latches properlyClose the window and check the handle turns and the latch engages without forcing. If it's too stiff to close properly, the strip is too thick for that gap — peel it off and swap to a thinner grade rather than leaving the window unable to lock securely.
DW-10Trim any excess and tidy upTrim off any strip that overhangs the corners with scissors for a neat finish. Wipe away any fingerprints from the glass or frame, and bin the backing paper offcuts.
DW-11Leave it to bond before heavy useAvoid slamming the window shut for the first 24 hours while the adhesive fully cures. After that, open and close it a few times over the next few days and press down any edges that start to lift.
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