Best Paint for Window Sills (Interior and Exterior)

Whether you have uPVC, concrete or wooden windowsills, choosing the right paint system for your specific substrate is paramount when it comes to a painted windowsill that not only looks great but stands the test of time.

Having used a variety of different paint systems over the years, I’ve been lucky enough (and sometimes unlucky enough) to find out which paints work best for different window sill types.

In this article, I’m going to pass 20 years of experience on to you so that you can find the best paint for your own windowsills.

With that being said, let’s jump right into it.

Quick look:

  • Best Overall: Sandtex Masonry Paint
  • Best for exterior wood windowsills: Sadolin Superdec
  • For interior wood windowsills: Johnstone’s Aqua Guard Satin
  • If your existing paint is peeling: Johnstone’s Pliolite Masonry Paint
  • Best for uPVC windowsills: Selemix Pro
  • Best gloss paint for windowsills: Zinsser Allcoat

6 Best Paints for Window Sills

1. Sandtex Masonry Paint

Best Overall

When it comes to window sills, you can’t beat Sandtex High Cover Smooth Masonry Paint. The smooth, even finish it delivers is top-notch. Its staying power is exceptional, even in challenging locations like properties right by the sea, where salt, wind, and rain are daily affairs.

The alternative, Sandtex 365 Masonry Paint, although a decent choice for some applications, can be hard on the roller. If you prefer an easy application and cleaning process, especially on detailed window sill work, I’d lean toward the High Cover Smooth Masonry Paint.

Compared to Dulux Storm Shield, Sandtex provides superior breathability and self-cleaning properties, crucial factors when choosing paint for window sills. It manages to offer a great finish, at a similar price point to Dulux, but with better performance.

While Emperor is often praised as the crème de la crème of masonry paints, it also comes with a hefty price tag. Sandtex offers an attractive alternative for window sill painting, being significantly more affordable and nearly as reliable.

In the chillier months, Sandtex doesn’t disappoint. Its performance in low temperatures is commendable, and it becomes shower-resistant in just 30 minutes. The coverage is impressive, essential for those window sills that demand attention to detail.

I’ve just wrapped up a project using Sandtex on window sills. The result was less splattering compared to Weathershield, and the application process was a dream. As a decorator with years of experience painting window sills, I can confidently vouch for Sandtex High Cover Smooth Masonry Paint.

Overall, it provides good opacity, breathability, durability, and ease of application.


  • Easy to achieve a smooth, even finish
  • Similar in price to the Dulux equivalent but has better performance
  • Easy to apply – doesn’t spatter during application


  • None

2. Sadolin Superdec

Perfect for exterior wood window sills

When it comes to painting wooden window sills, Sadolin Superdec is my top recommendation. This product is often underrated, but in my experience, nothing can match its longevity and flexibility.

First off, Superdec is self-priming, which makes the application process simpler. You only need to take care of any flaking or loose bits with a good rub down before you start painting.

Its coverage is impressive; a little goes a long way compared to cheaper alternatives. This means you’ll need less of it, even for large window sills. It’s even versatile enough to go over old oil-based finishes after a good rubdown.

One of the best attributes of Superdec is its durability. I’ve seen it remain unblemished even after a few years, and that’s no small feat. The finish it offers is always spot-on, providing a clean, polished look for your wooden sills.

Although it really looks good in black and other colours, like most water-based products, it’s not as effective in white.

While Superdec is a good performer, it sometimes requires three coats to bring out its best. I normally apply the first two coats one day and finish off the third the next to allow curing time. The wait is worth it though, especially considering its impressive 10-year lifespan on wood.

It’s also akin to Allcoat in performance. With the right colours, it provides excellent coverage. One of the hidden features of Superdec, not mentioned on the tin yet, is its suitability for UPVC surfaces, thanks to its new formula with improved adhesion.

The updated Superdec is also available in a vast range of colours, giving you endless possibilities to match your aesthetic preferences. Its quick and easy application process makes it manageable to give the recommended three coats.

Superdec positions itself as a satin finish paint, but it’s typically a touch flatter than your standard satin. That’s not a negative, just a characteristic to keep in mind when deciding on the final look you want for your window sills.

Recoating with Superdec should ideally be done between 12-16 hours for the best result.


  • It’s very flexible which means it can withstand expansion and contraction of the wooden substrate
  • It can last for 10 years if looked after
  • It’s self-priming so you don’t need to worry about buying separate products


  • It looks slightly flatter than satin despite being a satin
  • It takes 3 coats to achieve the best finish

3. Johnstone’s Aqua Guard Satin

Fantastic for interior wood window sills

For interior wooden window sills, my go-to is Johnstone’s Aqua Guard Satin. And here’s why.

First of all, Aqua Guard has immense coverage. I’ve found that even without an undercoat, it provides a quality finish. This puts it leagues ahead of its competitor, Dulux’s Diamond Satinwood, which I’ve found struggles to cover even after three coats.

Aqua Guard is especially effective for small areas like window sills. It does dry quickly, like most water-based paints, but you won’t need to hurry when working on a small area, making it a non-issue.

Despite its good adhesion, I still advise using the undercoat with Aqua Guard. This may not necessarily improve the initial application, but it significantly extends the life of the finish. Some decorators find that the flow isn’t top-notch so apply it with a damp brush to make it easier to apply.

While it might have slightly less coverage compared to Johnstone’s standard satin, Aqua Guard is more forgiving on your brushes and offers more hardwearing properties. It even gives the highly rated Caparol Satin a run for its money, proving more scratch-resistant, although with that being said, both are very hardwearing.


  • It goes for miles meaning you don’t have to load your paintbrush/roller up as often
  • Being water-based makes it low odour
  • It doesn’t ruin your brushes unlike some satinwood paints


  • Needs to be used in conjunction with the Aqua Guard undercoat for best results

4. Johnstone’s Pliolite Masonry Paint

If your current exterior window sill paint is peeling

For window sills that have previously been painted but now have peeling paint, I swear by Johnstone’s Masonry Pliolite.

Firstly, the Pliolite is self-stabilising so if the root of the problem has been solved then you will be fine with just the Pliolite after your prep work is done. It’s best applied with a mohair or foam roller for optimal results, and I always recommend giving it a good 24 hours between coats.

One of the major strengths of Pliolite is its hardwearing nature. As long as your preparation is solid, this paint is a workhorse that won’t let you down. In fact, its toughness is evidenced by its status as the number one choice for masonry paint in coastal locations, notorious for their harsh weather conditions.

An added bonus – it’s showerproof in just 20 minutes. Furthermore, it can dry in sub-zero temperatures, making it an excellent option if you’re looking to paint during the winter.

Another interesting point about Pliolite is that despite being solvent-based, it’s VOC compliant, making it a safer choice for your health and the environment.

If you’re willing to thin the first coat, it offers excellent opacity and coverage, on par with other industry leaders like Leyland.

In short, if you’re dealing with previously painted, now peeling window sills, Johnstone’s Masonry Pliolite is your best bet.


  • Can dry in almost any temperature
  • Incredibly durable – so much so that it’s typically used in coastal areas
  • It’s self-stabilising meaning it’s ideal for use on problem surfaces


  • None

5. Selemix 2K

Best for uPVC Window Sills

For uPVC window sills, there’s one product that outshines the rest, and that’s Selemix Pro. Let me elaborate.

I’ve used Selemix Pro for years and recently gave HMG PVC Pro a shot. But, honestly, it wasn’t up to the mark. I had a tough time achieving a decent spray pattern with my Devilbiss Prolite 1.3mm at 30 PSI. Worse still, the scratch test left me disappointed – I could scratch off the paint with my fingernail 24 hours after spraying.

Compared to that, Selemix Pro holds its own beautifully. It’s significantly cheaper than Kolorbond, and the finish is superior. I apply it with a sprayer, and the finish is pretty much unbeatable. To achieve the perfect finish, the magic ingredient is 1-490 thinners. Just remember to thin the Selemix to a maximum of 25%; any more and the opacity suffers.

The prep work for Selemix involves keying the surface with 320-grit sandpaper and cleaning it down with a panel wipe. It’s straightforward and sets you up for success.

As for durability, thanks to its increased UV resistance and being acrylic, the life expectancy is upwards of 10 years before any maintenance is needed, even in coastal areas. In terms of adhesion, it’s every bit as good as the well-loved Selemix Direct. So, in short, for uPVC window sills, Selemix Pro is the one you should use.


  • Easy to achieve an even spray pattern
  • Can last for 10 years
  • Very reasonably priced


  • None

6. Zinsser Allcoat Exterior Gloss

Best Gloss Paint for Window Sills

Finally, for the perfect gloss finish on your window sills, I can’t recommend Zinsser Allcoat Exterior enough. This oil-based paint is one of the most dependable options available.

I’ve had personal experiences with it that affirm its high quality. Back in 2014, I used it on wooden window sills and even now, the finish remains rock solid. Bear in mind that it can dry fairly quickly and sometimes leaves brush marks. With that in mind, it’s best to work quickly and use a high-quality brush.

The Allcoat Exterior offers excellent coverage. Black is a particularly good option for coverage. For a change from black to white, you might need three coats, but the results are worth it.

One thing to remember is the drying time. It usually takes around 5 – 7 days to fully cure so you’ll want to be careful around the sills during this period. And that’s for the oil-based variant only. I haven’t been overly impressed with the acrylic versions, particularly the grey water-based variant.


  • The finish remains rock solid even after 9 years
  • The black colour has incredible coverage
  • It’s got a high sheen which gives you a lovely glossy finish


  • Difficult to achieve good coverage if going over a dark colour with a light colour