Best Paint for Exterior Window Sills UK Review 

Thanks for taking the time to read our review on the best types of paint for exterior window sills. The first consideration should be how you want your window sills to look. When you look at the windows on your house, there will of course be the glass, the actual window frame and the sills.

In most homes throughout the UK there will be some form of double glazing and for the majority of home owners that will be uPVC. Typically that colour will be white though there are now some interesting coloured options available. uPVC is popular because it needs little maintenance and it is simple enough to keep clean with a damp cloth, unless it is really old.

What is a Window Sill?

The window sill, also commonly known as a window ledge is the bottom of the window. It looks like a shelf and is usually flat and sticks out right at the bottom of the window. There is one on the outside and one on the inside. If you have double glazing installed the internal window sill will usually be made of matching uPVC.

External window sills are made when the house is being built, and they are usually made of some type of concrete. Their main purpose is to keep the windows in place. They also help prevent drafts and moisture from getting into the home. They are therefore an important part of the construction of your home.

As mentioned earlier, external sills/ledges are made from stone, concrete, cast stone and other non-porous materials. You will notice that these sills are installed with a slight slope to help water drain away from the windows and the house.

Best Paint for Outside Window Sills

For external window sills you will need some type of masonry paint. If the window sills are new, you will also need an external primer first and then the masonry paint. Just below we have provided a masonry paint comparison table.

Masonry Paint Comparison Table


0.75L Size

90% buyer satisfaction based on 12,000+ buyer reviews


0.75L Size

90% buyer satisfaction based on 1,500+ buyer reviews


0.75L Size

92% buyer satisfaction based on 100+ buyer reviews

How to Paint Your Outside Window Sills?

List of Steps

Step 1 - Dust Sheet & Masking Tape

Painting by its nature is messy. It is always a good idea to put down a dust sheet on the ground to catch any accidental spills and splashes. If painting sills higher up in bedrooms it isn't possible to do that so more care is required.

You should also use masking tape to protect the window frame and any brickwork from getting painted as this can look very untidy.

Step 2 - Fungicidal Wash & Sandpaper to remove dirt and Flaking

If you have flaking paint on your sills use a scraper and sandpaper to remove those. The smoother you can get your sills the better they will look. This is a boring job and time consuming but worth the effort for a much better finish. I have often used a power washer to get the rough off, if the surface is very dirty.

Step 3 - Fill any Gaps

Natural wear and tear will cause small holes and cracks in your sills. This is a good time to fill those. Use an external filler and we would recommend Polycell Plcwf Weatherproof Filler which is a top notch product for this type of work.

Fill in any cracks and holes and then sand those down. Finally do a brush to make sure you have a dust free surface.

Step 4 - Stain Removal

Many older window sills may have algae growing on them. That just happens over time. A good fungicidal wash such as Everbuild 404 will do an excellent job of removing that. You paint it on and leave it for a day and then wash it off to leave clean sills.

Step 5 - Prime

Primer is used to give you the perfect surface for paint. You have to use these on any surface that has not been painted before. We also think it is a very good idea to prime old surfaces as well as new paint struggles to stick to older paint.

The one we would recommend is the Zinsser ZINBE123500 Bulls Eye Primer as it is one of the best on the UK market. It only usually needs one coat and then you need to leave that for around 4 hours to dry before any paint can be applied.

Step 6 - First Coat

Finally you can get to your first coat of paint. Most people opt for white but the colour choice is really down to you. Brush or use a roller for the first coat. Avoid too much paint on the brush as this can cause bubbles on the surface.

Masonry paint dries quickly but leave 4 hours between coats as it will be dry completely by then.

Step 7 - Second Coat

After 4 hours apply the second coat, allow 4 hours to dry and then remove any masking tape. Your sill should be looking great.

Tips for Painting Your Outside Window Sills

A little bit of planning will go a long way. We know it is hard in the UK to get two dry days in a row. Your best chance is ideally in the Spring or Summer. Most homes will have outside window sills upstairs and also downstairs. The number of those will vary but there will be usually at least 7 or 8.

Our advice is to spend the first day cleaning, sanding and filling all the window sills to get them ready for paint. If you have enough time and energy, then also apply a coat of primer. On the second day you can do a first paint coat in the morning and a second coat in the afternoon.

Do the higher window sills first as any dust etc will fall down on to the sills below and double your work.

Always stay safe when using ladders.

Options to Painting Your Outside Window Sills

Many home owners get fed up with constantly having to maintain their external window sills and are looking for alternatives. These include:

  • Aluminium
  • uPVC
  • Marble
  • Ashlar
  • Timbers

These are placed on top of the existing sill and then sealed. The solutions vary in price and can get quite expensive.

About Us



Geoff Magee


As well as our many tool reviews, we have also included a whole range of articles, on how to use them. This will include the many tasks that you may have to do at home. That could include putting up a shelf, drilling through tiles, drilling through concrete, laying carpet, fixing a leaking tap, and just about any other thing that you can think of.

The site is managed and run by myself Enda, an electrician by trade, and by my friend Geoff, a painter with many years of experience. We have done house renovations, construction builds and extensions, loft and garage conversions, conservatories, fencing, path making and just about any other job in the construction and building industry.

Between us, we have a lot of experience, and we are more than happy to share that with you here.

Thanks for reading our best paint for exterior window sills article and we hope it has given you a better insight into the world of painting. If you would like some more information on painting equipment you could have a look at our article on Painting and Decorating Tools.

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