Free a stuck sash window by breaking old paint seals and easing the frame gently, without forcing or damaging the timber.
SW-01Clear and protect the areaRemove curtains, blinds and anything sitting on the sill. Lay a dust sheet over the sill and the floor below to catch paint flakes. Open a door or another window for ventilation if you can, since scraping old paint creates dust.
SW-02Check what's under the paintCut a small flake off with a utility knife and look at the layers before you start scraping properly. If the house was built or decorated before 1960, treat any old paint as possibly containing lead. Keep any scraping damp rather than sanding dry, and wear an FFP3 dust mask and gloves.
SW-03Score the paint seal around the sashRun a stripping knife or window scraper along every edge where the sash meets the frame: both sides, the top rail, and the meeting rail where the two sashes overlap. Do the inside face and the outside face too if you can reach it safely. This breaks the paint film gluing the sash shut.
SW-04Score the parting bead and staff beadThe parting bead sits in a groove between the two sashes. The staff bead holds the inner sash against the frame. Run the knife along both, on each side of the window, to free any paint bridging them to the sash.
SW-05Break the seal at the cornersPush a wide flat chisel or a purpose-made window-opening tool into the gap between the sash and frame at the bottom corners. Tap it gently with a rubber mallet to lever the sash away from the frame, working a little at each corner rather than forcing one side. Never strike the frame directly with a metal hammer, as it will crush the timber.
SW-06Tap the sash free along its lengthHold a scrap block of wood against the sash to spread the load, then tap along the bottom rail with the mallet to loosen the whole width evenly. Move up to the top sash and repeat if that one is also stuck. Stop as soon as you feel movement rather than continuing to hammer.
SW-07Ease the sash up and downOnce it moves, work the sash slowly through its full travel several times to break any remaining paint bond. If it binds at one point, stop, go back to that spot, and re-score the paint there rather than forcing it through.
SW-08Clean out the running channelsBrush loose paint flakes and old dust out of the channels the sash slides in. Wipe with a damp cloth rather than a dry brush if you suspect the paint contains lead, so dust doesn't become airborne.
SW-09Lubricate the runnersRub a candle stub or a proper sash lubricant stick along both sides of the channel and along the edges of the sash that touch the frame. Run the sash up and down a few times to work the lubricant in.
1 each · Sash window lubricant stick (or candle stub)
SW-10Tidy up and dispose of the wasteFold the dust sheet inward to trap the paint flakes, then bag it. If you suspect lead paint, double-bag the waste and check your local council's guidance on disposal rather than putting loose scrapings in general recycling. Wipe the sill and surrounding area with a damp cloth.