Fix a sticking timber sash window

Free a sticking sash window by easing the sash, freeing the pulleys, and lubricating the running channels.

AB-01Prepare the area and check for lead paintLay a dust sheet under the window to catch debris and old paint flakes. Put on a dust mask and eye protection before you start. If your home was built before 1960, assume the existing paint contains lead and take extra care not to create dry dust.

RULES

1 each · Dust sheet

Buy:ScrewfixB&QToolstationAmazon

1 pack · Disposable dust masks (FFP3)

Buy:ScrewfixB&QToolstationAmazon

1 each · Safety glasses

Buy:ScrewfixB&QToolstationAmazon

KNOW THE RULES

Paint on windows in homes built before 1960 often contains lead. Dampen it before scraping or sanding, wear a proper dust mask, and bag up dust and scrapings as hazardous waste rather than putting them in normal rubbish.

AB-02Break the paint seal around the sashRun a filling knife along every edge where the sash meets the frame, top, bottom and both sides. This breaks any paint bond holding it shut without tearing the wood underneath. Work slowly with light pressure, don't lever or force it.

1 each · Filling knife (40mm blade)

Buy:ScrewfixB&QToolstationAmazon

AB-03Test the sash and find where it bindsOpen and close the window through its full range of movement. Note exactly where it drags — top corners, the bottom rail, or all the way down one side. This tells you whether the cause is swollen timber, paint build-up, or a stuck pulley wheel.

AB-04Remove the staff bead and lift out the sashUse a chisel to gently prise the thin staff bead away from the frame, starting in the middle of the bead and working outwards. Keep the bead intact where you can, as you'll refit it later. Lift the sash free once the bead is clear and support it so it doesn't fall or twist.

1 each · Chisel (25mm)

Buy:ScrewfixB&QToolstationAmazon

AB-05Ease the tight spotsWorking only on the edge that was binding, plane or sand off a millimetre or two at a time. Refit the sash to check the fit often — little and often is much safer than taking off too much in one go. Round off any sharp edges left by sanding with fine-grit paper.

1 each · Block plane

Buy:ScrewfixB&QToolstationAmazon

1 sheet · Sandpaper, 120 grit

Buy:ScrewfixB&QToolstationAmazon

AB-06Check and free the pulley wheelsLook inside the frame channel for the small pulley wheel near the top of each side. Spin it by hand — it should turn freely. If it's stiff or clogged with old paint, clean it out with a soft brush and add a drop of light oil.

1 small bottle · Light machine oil

Buy:ScrewfixB&QToolstationAmazon

1 each · Soft-bristle brush

Buy:ScrewfixB&QToolstationAmazon

AB-07Check the sash cordsWhile the sash is out, look at the cords on both sides. If they're frayed, cracked, or the sash won't stay up on its own without help, the cords need replacing — that's a separate job, so make a note for later. Don't refit a sash on cords that look close to failing.

AB-08Refit the sash and staff beadLower the sash back into the frame and check it slides smoothly with no new tight spots. Refit the staff bead, tapping it gently back into place with panel pins if the old ones came loose. Leave a hair's width of clearance between the bead and the sash so it can still move freely.

1 pack · Panel pins, 20mm

Buy:ScrewfixB&QToolstationAmazon

1 each · Hammer

Buy:ScrewfixB&QToolstationAmazon

AB-09Lubricate the running channelsRub candle wax, beeswax, or a proprietary sash lubricant along both edges of the sash and inside the frame channels. This cuts friction without attracting the dirt that oil would. Open and close the window a few times to work it in evenly.

1 each · Sash lubricant or candle wax

Buy:ScrewfixB&QToolstationAmazon

AB-10Test the full range of movementOpen and close the sash fully several times, checking it runs smoothly top to bottom. It should stay up on its own if the cords and weights are working properly. If it still catches anywhere, go back and ease that spot a little more.

AB-11Seal bare wood and tidy upIf you've exposed any bare timber during planing or sanding, prime and paint it before the next damp spell to stop it swelling again. Fold the dust sheet with the debris inside and bag up paint scrapings for disposal. Wipe down and put away your tools.

1 small tin · Wood primer

Buy:ScrewfixB&QToolstationAmazon

1 small tin · Trim paint, matching colour

Buy:ScrewfixB&QToolstationAmazon

Some links may earn us a small commission at no extra cost to you.

Save this as a project

Back to all guides