A modern window should open easily, close tightly and keep the cold out. Over time, constant opening, tilting for ventilation and heat from the sun make the sash drop: it catches the frame, the handle turns stiffly and in winter a draught creeps in past the seal.
On a standard tilt-and-turn window most of these faults can be fixed with a hex key. The steps below cover standard hardware; for unusual designs call a fitter.
What you will need
Important: Adjust half a turn at a time and check how the sash moves after each change. Never fully remove the hinge screws or take the sash off: it is heavy, and with a glass unit it is dangerous.
Step 1
Inspect the window and pin down the fault
First work out what exactly is wrong. Open and close the sash and see where it touches the frame. A handy test: trap a sheet of paper between sash and frame in several places. If it pulls out easily, the compression is too weak.
The adjusting screws are on the top hinge (the stay arm), the bottom hinge and the cam bolts along the handle-side edge of the sash.
Step 2
Correct a diagonal drop
If the sash hangs crooked and catches the frame at the bottom on the handle side, turn the screw in the top stay arm (reachable with the sash open). Clockwise pulls the top corner towards the hinges and lifts the opposite bottom corner; anticlockwise lowers it.
Keep going until the gaps between sash and frame are even all round.
Step 3
Shift the sash sideways
If the sash catches the frame on one side, use the horizontal screws on both the top and bottom hinges. Turn them the same way by roughly the same amount, so the sash moves parallel towards or away from the hinges.
Step 4
Set the height
The vertical screw sits on top of the bottom hinge, under the decorative cover. Clockwise raises the sash, anticlockwise lowers it. Aim for the sash to sit centred in the frame without rubbing at the top or bottom.
Step 5
Adjust the compression
Sometimes the sash sits straight but still lets in a draught, or the window opens easily but is hard to close. Then change the compression with the cam bolts on the edge of the sash. Turn each one with a hex key or pliers: towards the outside gives a tighter winter setting, towards the room a lighter summer one.
Set all the cams the same, otherwise the seal will be compressed unevenly.
Step 6
Lubricate the hardware and seals
After adjusting, clear dust from the hardware. Treat the moving parts, cam bolts, keeps and handle mechanism with WD-40 Smart Straw: it creeps into gaps, frees sticking parts and displaces moisture. For longer-lasting lubrication you can add WD-40 Specialist White Lithium Grease to the same points. Do not flood the hinges with the adjusting screws.
Wipe the rubber seals and treat them with WD-40 Specialist Silicone so they stay supple and do not freeze to the frame in winter. Wipe off the excess and keep products off the glass.
Tip: Switch windows to the winter compression setting in October and back to summer in spring: a seal kept fully compressed all year loses its spring sooner.
What next
Inspect, clean and lubricate the hardware twice a year, before the cold sets in and after winter. If the sash still catches or the handle still sticks after adjustment, the hardware is probably worn and a fitter is the best option. WD-40 Specialist Silicone also suits the seals on doors and balcony units.
These uses come from the experience of WD-40 users in many countries. Always follow the instructions and warnings on the product label.
More guides in «How to use».