How do I service uPVC windows once a year?

Almost every uPVC window fault that costs money — a sheared gearbox, a dropped sash, a draughty seal, water on the cill — starts as friction or a blocked drain. Both are prevented by a short annual routine that nobody does.

What you'll need

• A vacuum with a crevice tool
• A thin probe or wire
• Light machine oil for moving metal
• Silicone grease or spray for rubber
• A Pozidriv screwdriver
• A cloth and cream cleaner

Step by step

1. Start with the drainage.Find the slots on the outer face at the bottom of each frame, often behind small covers, and clear them with a wire. Pour a little water in to confirm it comes out.
2. Vacuum the channels.The rebate the sash closes into fills with grit, insects and pollen. That debris is what stops a gasket compressing and what grinds the stays.
3. Wash the frames.Warm water and a little washing-up liquid. For ingrained grey marks on white uPVC, a dedicated uPVC cleaner. Never abrasive pads or scouring cream on a textured or foiled frame.
4. Check and tighten the stay screws.Every screw on both friction stays. They loosen over years and a loose stay lets the sash sag, which is the root of most alignment complaints.
5. Oil the moving metal.A drop of light machine oil on the stay pivots, the cams, the keeps and the gearbox. Work the handle a few times to spread it.
6. Do not oil the gaskets.Oil degrades rubber. The gaskets want silicone grease or a silicone spray, which keeps them supple and stops them sticking to the frame in frost.
7. Check the handle and lock action.It should turn with light pressure through its full travel. Any stiffness is friction that will eventually shear the gearbox — find it now.
8. Test each gasket with a paper strip.Close the window on paper at several points around the sash. Anywhere it pulls out freely is a gasket or a keep needing attention.
9. Check the glazing beads and packers.A bead that has come loose lets the glass move and can crack a sealed unit. Press each one; it should be firm.
10. Look at the external sealant.The mastic joint between frame and masonry perishes on the exposed elevations first. Rake out and replace failed sections while they are small.
11. Note anything you cannot fix.A misted unit, a hairline crack in the frame, a stay that is corroded solid. Writing them down means they get dealt with rather than forgotten.

Tips

• Do all the windows in one go, on a dry day in spring. It is a two-hour job for a whole house and it is the highest-value maintenance in the building.
• Keep a note of which windows have which stay lengths and handle types. When one fails you will not have to measure in the rain.
• If a window has never been serviced and is twenty years old, expect to find at least one blocked drain and one loose stay screw.

Common mistakes

• Using WD-40 on window mechanisms — It is a water dispersant rather than a lubricant. It flushes out the grease the gearbox was assembled with, leaves a thin film that attracts dust, and the mechanism ends up stiffer within a few months.
• Cleaning uPVC with an abrasive cream — White uPVC has a smooth outer skin. Scouring it leaves microscopic scratches that hold dirt, so the frame goes grey faster and can never be cleaned properly again.

Keeping on top of it

• Clear the drainage slots and check water runs out (Twice a year)
• Vacuum the frame channels and gasket rebates (Annually)
• Oil the stays, cams, keeps and gearbox (Annually)
• Silicone grease all gaskets (Annually)
• Check and tighten every stay and keep screw (Annually)
• Inspect the external mastic joint (Annually)

Questions people ask