How do I look after wooden windows and doors?

The annual check and the small repairs that make wooden windows last a century rather than a decade.

Difficulty: intermediate
Time: 4 hr
Read: 2 min
Safety: caution

Short answer

Check the bottom rails and the joints each summer — that is where water sits and rot starts. Small repairs caught early cost almost nothing; a rotten sill is a joinery job.

Well-maintained wooden windows outlast plastic ones by a long way. Neglected, they rot in a decade. The difference is a couple of hours a year and knowing which few centimetres to look at.

Safety

Paint in houses built before 1980 may contain lead. Do not dry-sand or heat-strip it without proper precautions — use wet sanding, a mask rated for the work, and keep children and pregnant women away. If in doubt, have the paint tested.

What you'll need

Paint or wood stain
Filler or wood repair resin
Sandpaper
Brush
Sealant (optional)
Screwdriver

Step by step

Inspect in summer, when everything is dry.Wood swells in winter and hides gaps. Dry conditions show the true state and allow immediate repair.
Press the bottom rails and sills with a screwdriver.Gently. Soft wood that gives is rot. This is where water sits, and it is where nine out of ten failures begin.
Check the joints at the corners.Open joints let water into the end grain, which absorbs it fastest. A bead of flexible sealant on a sound joint prevents a great deal.
Look at the putty or beading around the glass.Cracked and missing putty lets water behind the glass and into the frame. Rake out the failed sections and replace.
Cut out and repair small rot immediately.Remove all the soft wood back to sound timber, treat with hardener, then fill with a two-part wood repair filler. Caught at this size it is a half-hour job.
Repaint before the existing coat fails.Once paint cracks, water gets in and the wood beneath goes. Repainting on a schedule is far cheaper than repairing rot. Typically every five years or so.
Keep drainage holes clear.Small holes in the bottom of the frame let trapped water out. Blocked with paint or dirt, water sits inside the frame.
Oil the hinges and check the fittings.Two minutes. Seized hinges get forced, which damages the frame around them.

Tips

Microporous paint lets the wood breathe and lasts better than a hard gloss that traps moisture underneath.
Repaint the bottom rail more often than the rest. It takes the most weather and it is where the failure starts.
For sash windows, the cords are the usual failure. Replacing them is a specific but well-documented job.

Questions people ask

How often should wooden windows be painted?

Roughly every five years, and repaint before the existing coat cracks. South and west-facing windows weather faster and may need it sooner.

Can I repair rotten wood myself?

Small areas, yes — cut out all soft wood, treat with hardener and use a two-part repair filler. Extensive rot in a sill or rail needs a joiner.