Painting timber windows

Timber windows, including sash windows, can deteriorate over time, and this is particularly true of those that are exposed to the elements. Wind, rain and sunlight – not to mention wind-borne spores and general grime – all contribute to the breakdown and deterioration of all materials.

This means that you may need to repaint your sash windows from time to time. How regularly you need to paint sash windows will depend on various factors listed below. In this article, we outline how to paint sash windows, with tips on how to prevent any unforeseen issues, in order to make your windows last as long as possible.

How regularly do you need to repaint sash windows?

When cleaning your sash windows, it’s important to look out for any damage to the paintwork or timber and repair it as soon as possible, to avoid further damage.

The performance of wooden sash windows, as well as timber doors, can be protected through a maintenance coating to increase the barrier between the wood and the elements, either when the coating has been damaged, or around every 5 years.

There are various factors that affect the frequency of maintenance cycles, including climate conditions, coating type and window position. Timber whose orientation is North facing and is predominantly sheltered will generally require less maintenance than South facing timber on window sills or beads. Opaque paint finishes will also require less frequent maintenance than stain finishes.

Typical maintenance cycles for different climatic conditions and coating types are illustrated in the table below.

Coating Type Window Position

Moderate Climate:

Non Coastal areas & ground floor

Hard Climate:

Within 1/2 mile of coastline, second floor or above, or on a hillside

Extreme Climate:

High altitude or exposed coastal areas

White or light
coloured paint

Set Back

On Facade

10 Years

8-10 Years

7 Years

5-7 Years

7 Years

4-6 Years

Dark coloured paint
and dark translucents

Set Back

On Facade

6-8 Years

4-6 Years

4-6 Years

4-6 Years

3-4 Years

3-4 Years

Light translucents such as light oak and pine

Set Back

On Facade

3-4 Years

2-3 Years

2-3 Years

2-3 Years

1-2 Years

1-2 Years


Tips for painting sash windows

For painting sash windows, a good quality water based, microporous paint such as Teknos should be used. Timbawood windows, for example, are factory spray finished or hand painted using Teknos microporous paint system. Follow our tips below to ensure you achieve a great finish when you paint sash windows.

Before painting your sash windows, remove any loose coating material from the paintwork and gently abrade with a fine to medium grade sandpaper or foam pad, taking care to sand in the direction of the grain. Frames should not be rubbed down with coarse sandpaper. Ensure that any ‘grey’ timber that has been damaged by ultraviolet light is removed back to a clean, bright surface.

The next step when painting sash windows is to wash down the abraded paintwork to remove any dust, dirt or other contaminants using a mild detergent solution. You should then rinse with clean water before allowing the timber to thoroughly dry.

For minor flaking or peeling:

In DRY weather brush apply a single coat of a suitable maintenance coating (i.e. a water based, microporous exterior grade paint such as Teknos Aquatop 2600), using a long haired synthetic bristle brush to the abraded areas, ensuring any areas of end grain are sufficiently coated, and allow the coating material to dry.

Be aware that you’ll want to avoid sticking when painting your sash windows, which can happen if the layers of paint are too thick. To avoid this, make sure you use even layers.

Allow the first coat of paint to dry for at least 4 hours before lightly sanding the affected area with a fine grade sandpaper or foam pad and repeating coating as above. Two coats may well be required to build up the coating film sufficiently to achieve an even coating.

For more widespread damage:

Where moisture has penetrated joints/end grain or cracks have developed in the corner joints of the frame/casing or on the window sill, the damaged areas of the sash window should be coated with a primer and any open joints filled with Teknos V Joint Sealer or a two part polyurethane filler/hardener. Once dry, rub down to a flush finish before applying one or two coats of Top coat to your sash windows as above.

NB. Resin exudation – Resin should be left to dry out and crystallise into a white powder before being brushed away with a semi-rigid nylon/natural bristle brush. Repainting may not be required as resin can often pass through paint coatings without damage.

In some cases, your windows may have such significant damage that they need to be repaired or replaced rather than simply repainted. We specialise in the finest single and double glazed replacement timber sash windows and casement windows for period properties throughout the ages, as well as offering repair services for heritage windows.

If you have any questions about your timber windows and doors, or you would like a free quote, please get in touch to speak to one of our specialists.