How to paint wooden window frames.

Windows combine timber, glass, putty or sealants, metal hardware and moving joints. A coating can protect sound wood, but it cannot rescue rot, failed glazing or trapped water. In exposed Nottinghamshire weather, the inspection and timing matter as much as the colour.

Inspect before scraping

• Probe suspicious soft areas gently; do not paint over rot.
• Look for open joints, cracked putty, failed sealant and water staining.
• Check that opening sections move and close correctly.
• Identify drainage slots and keep them clear.
• Consider the age of old paint before creating dust.

If the timber is soft, joints have opened or the glazing detail has failed, a joiner’s repair may be needed before a decorator can sensibly finish it. Paint should protect sound work, not conceal structural or joinery problems.

Choose the weather window

Exterior coating needs a dry surface and conditions inside the paint’s stated temperature and humidity range. Avoid rain, dew, intense direct sun and a cold evening immediately after painting. Timber moisture level matters more than a forecast icon, and a realistic schedule may need to move when the surface is not suitable.

Preparation

1. 1
   Clean.

   Remove grime, algae and chalking with methods suitable for the existing coating.

2. 2
   Remove failed paint.

   Scrape loose edges without damaging sound wood or glass. Feather boundaries rather than leaving sharp ridges.

3. 3
   Repair the substrate.

   Replace failed putty or sealant with compatible materials and allow them to cure as specified. Repair rot properly or replace affected timber.

4. 4
   Sand and remove dust.

   Key sound gloss and smooth repairs, taking lead precautions on older coatings.

5. 5
   Prime bare wood.

   Pay attention to end grain and repaired areas. Follow the window and paint system requirements.

6. 6
   Undercoat and finish.

   Use an exterior-rated system, keeping coats thin at joints and moving edges.

How neat should the glass line be?

Traditional painted timber glazing systems may require the coating to lap very slightly onto the glass to seal the putty edge. Modern glazing beads and sealants have different requirements. Follow the window and coating manufacturer’s detail rather than applying one rule to every window.

Avoid painting the window shut

Open sections at the stages recommended for the product, remove paint from hardware and do not bridge drainage paths. Keep meeting surfaces thin and allow adequate cure time before closing tightly. Fresh coatings can block together even when they feel touch-dry. Do not lean from windows or use an unstable ladder; upper-storey work may require properly selected access equipment and a competent professional.

Interior window frames

Condensation can still affect the inner frame. Clean thoroughly, repair failed coating and investigate persistent moisture. Use a trim finish compatible with the existing paint and any flexible sealants. Do not paint rubber seals or operating hardware.

Maintenance beats wholesale stripping

Inspect exterior joinery at least annually, especially lower rails, sill ends and shaded elevations that stay wet longer. A small coating split repaired while the timber remains sound is easier than waiting for water to enter joints. Wash dirt away gently and avoid sealing over wet wood. Keep a record of the coating system and colour so local maintenance remains compatible.

Window-painting FAQs