Clean, lubricate and adjust the hinges and keep on your uPVC window to stop it sticking or catching.
WD-01Work out exactly where it sticksOpen and close the window slowly through its full range and watch where it catches. Note whether it binds at the top, bottom, or where the sash meets the frame near the handle. This tells you whether the fix is a hinge, a keep, or dirt in the track, so you don't adjust the wrong thing.
WD-02Clean the frame, sash and hingesWipe down the rubber seal, the frame edge, and the hinges with a damp cloth to remove grit and old grease. Use a small stiff brush to get into the hinge and the keep (the metal catch the sash locks into). Grit build-up is one of the most common causes of a sticking uPVC window and costs nothing to fix.
WD-03Lubricate the hinges, pins and lockSpray a light coat of silicone-based lubricant into both hinges, along the hinge pin, and into the multi-point locking mechanism and keeps. Do not use an oil-based spray lubricant, as it can attract dirt and swell rubber seals over time. Open and close the window a few times to work the lubricant in.
WD-04Check and tighten the hinge screwsLoose hinge screws let the sash drop slightly and catch on the frame. Check every screw on both hinges with a cross-head screwdriver and tighten any that turn easily. Do not overtighten into uPVC, as this can strip the screw hole.
WD-05Adjust the hinges if the sash has droppedMost uPVC casement windows have adjustable hinges with small screws or an Allen key socket at the top and bottom, usually 4mm. Turning the top hinge screw moves the sash up or down; the bottom hinge often adjusts side to side. Make small quarter-turn adjustments and test the window after each one.
WD-06Adjust the keep if the sash won't engage smoothlyIf the window catches right as it closes, the keep (the metal plate the locking pins engage into) may be slightly out of line. Loosen the keep's fixing screws a little, tap it a millimetre or two in the direction needed, then retighten. Close the window fully to check the sash meets the frame evenly all round before you finish.
WD-07Test the full open-close cycleOpen the window fully, close it, and lock it, repeating this several times to make sure the sticking has gone and the lock engages without force. If it still catches, go back and make another small hinge adjustment rather than forcing the handle, as forcing a multi-point lock can damage the mechanism.
WD-08Wipe down and tidy upWipe off any excess lubricant from the frame and glass so it doesn't attract dust. Put your screwdriver and Allen keys away somewhere you'll find them, as window hinges often need a small seasonal tweak as the weather changes.
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