Best Waterproof Paint for Exterior Walls

Updated Jun 6, 2024 | Posted Oct 11, 2023 | Professional insight, Product Advice | 0 comments

The best paint for exterior walls is masonry paint. However, some masonry paint products are far more waterproof than others. Moreover, a good masonry paint needs to have a certain level of breathability, otherwise it can actually trap moisture in your walls.

Waterproof paint will act as the first line of defence on your home against the elements. Not only will it drastically increase the lifespan of your walls and block moisture, but in some cases, it can also make your home more energy efficient. If your walls hold water, then heat from the building will dissipate more quickly and your heating bills will be higher.

In this quick blog, I’m going to talk through what is needed from a waterproof paint, what you should look for, and then recommend a couple of products.


What You Need from a Waterproof Masonry Paint


Most masonry paint products are polymer-based (plastic), which although have a certain degree of water resistance, do not repel water like silicone-based paints do.


Silicone isn’t just waterproof, it’s water repellent, which means water beads up on its surface and runs off. Not only are your walls better protected from moisture, but they also stay cleaner. A dirty mark from a muddy football is likely to disappear from your wall next time you have a heavy downpour.

Silicone is also a lot more breathable than normal polymer-based paint, meaning moisture is never trapped. So, regardless of whether you go for one of my recommendations or not, if you want a truly waterproof paint for exterior walls, then you should opt for a silicone-based masonry paint.


The Best Waterproof Paint for Exterior Walls


I’m going to keep it nice and simple and give you the two masonry products I think you should consider. The first is a good quality trade paint that will do everything you need it to do, and is available at a reasonable price.

The second genuinely is the best waterproof paint for exterior walls (based my experience as a Professional Decorator and the research I have conducted over the years). However, it comes with a premium price tag.

Just have a look at what I say about each and then choose accordingly.

Wethertex AP77

Wethertex masonry paint goes under the radar a little bit, but it really shouldn’t. AP77 is manufactured in Yorkshire and costs the same as the standard trade masonry paints on the market. However, it isn’t a standard masonry paint!

This is a silicone-based paint, so is very waterproof and breathable. You’ll find it easy to apply, good opacity, and leaves a nice matt finish.

It does everything a masonry paint needs to do and it’s perfect for exterior walls. It’s a product I use regularly the during the summer months, and one I have great faith in.

The colours seem rich, and it doesn’t seem to bleach with the sun like some other paints do.

Emperor Paint Masonry Paint

Emperor Paint is probably the best waterproof paint for exterior walls. It is very expensive, but this is down to the quality of resins they use in the paint. It’s described as ‘hydrophobic’, meaning it repels water. It’s also very breathable.

From an application and finish pint of view, this masonry paint performs as well as anything else I’ve tried. It has great opacity, it is easy to apply, and is lovely and deep in tinted colours.

The longevity of the paint is very impressive. You should expect a painted surface to last 25 years apparently, which is quite remarkable. We’re talking about needing to paint an exterior wall roughly three or four times in a person’s life! Although I’ve only been decorating 20 years, so I haven’t seen it firsthand.

The heat retention properties of this paint are also well documented and tested. By keeping your exterior walls as dry as Emperor Paint does, your home is likely to take less energy to heat.

Although expensive, we do have a code You can use, which entitles you to some discount. Use DFUK at the checkout.

A Waterproof Clear Coat for Exterior Walls


I thought I’d include Emperor Masonry Crème to the blog as it’s another waterproof protective coating. There may be similar products out there, but I’ve only ever used Emperor, so this is the one I can vouch for.

Emperor Masonry Crème is a milky liquid that you apply to exterior walls. It dries clear, so it looks like you haven’t coated it with anything. The product basically acts as a waterproof membrane, that remains breathable. It is expensive, but one thin coat is enough to waterproof exterior walls, so it does cover a large area.

To describe it as “water repellent” would be understating things. You can literally see the water being repelled from your wall.

It also helps to prevent algae growth and keeps your wall clean. I’ve used it on brick, breeze block, and over painted render. It’s quick and easy enough to apply too.

Again, we do have a coupon that entitles you to a small discount. Use DFUK at the checkout.

best wat to waterproof exterior walls
The best waterproof paint for exterior walls

Mike Cupit quickly talks through his recommendations.

The Best Tools to Apply Masonry Paint to Exterior Walls


Regardless of whether you use one of the water-repellent paints on this blog, or you go with a normal masonry paint, having the correct tools for the job will help.


Paint Roller

A long pile roller and a sturdy pole will help you to apply generous coats of masonry paint and really work it into every gap in your wall. This is important to make a fully waterproof layer. My choice would be a Purdy Colossus. Get the 9 ninch for painting exterior walls.

Paint Brush

You’ll also need a brush with a thick stock that holds its shape. Avoid those floppy thin 4-inch brushes labelled “masonry brush” in your local DIY shop as they’re useless.

If you want a cheap, but good brush, look for the Kana Professional Synthetic. However, the best brush for applying waterproof masonry paint to exterior walls is Purdy Monarch Elite XL. It may be expensive but look after it and it will last for years.




Can Masonry Paint be Used Inside?

Masonry paint, particularly those mentioned on this list, are waterproof, so you’d expect them to make a good alternative to interior emulsion for rooms like bathrooms or kitchens. However, I would advise against it.

Masonry paint contains a lot of fungicide so it can resist algae growth on exterior walls. This fungicide can be harmful when applying the paint in an enclosed area such as a bathroom. For this reason, it just isn’t safe to use masonry paint inside.


Does Masonry Paint Need an Undercoat?

It’s very rare that you encounter a masonry paint that requires an undercoat on exterior walls. You should always check the data sheet any way, but Crown Dulux, Johnstone’s Emperor, Zinsser, Wethertex and many of the others can be painted directly to your wall. The only time you’d really use a separate product is if your wall is chalky and unstable. In a case like this, you’d use a stabilising solution.

Moreover, if you were to use some sort of undercoat before applying one of the masonry paints recommended on this blog, then you may affect the paint’s ability to let your masonry breathe. In essence, you’re trapping moisture in your exterior walls, which can cause damage.


How do you prepare Exterior Walls before applying masonry paint?

The first thing you should do is scrape or sand any flaky paint to remove it, then prime any unstable masonry with stabilising solution. I use Zinsser Peel Stop more often than not. I then make any repairs to the wall using a good quality masonry paint.

Algae should be treated with a fungicidal wash to prevent it from seeping through your paint while it is still wet. Once at this stage, you’re free to apply a good quality waterproof paint.


Is Masonry Paint Resistant to Mold, Mildew, and Algae Growth?

In short, yes. All masonry paint products contain large amounts of fungicide, meaning they are resistant to mould, mildew, and algae growth. Some more so than others. The highly waterproof paints recommended on this blog are very effective, simply because your painted exterior walls will not hold onto water.

Cheap polymer-based paints are the other end of the spectrum. As a rule, the cheaper the paint, the less binder, so moisture can penetrate, and the surface stays wet for longer after rain. This gives mould, mildew, and algae chance to take advantage and grow. The more waterproof your paint, the longer your exterior walls will look clean.

 Final Thoughts


I hope this has helped. Let’s face it, making painted exterior walls waterproof should be the priority for every homeowner. By using one of the products on this list, your finish should last well and protect your home.


Work Carried Out by Other Decorators Using Waterproof Paint

Cal’s Decorating

I’ve been using Weathertex Ap77 for around 5 years. It t has great opacity, sticks like glue, and is more weather resistant than most other masonry paints. It is ideal for stone walls or any property that doesn’t have a cavity to help moisture escape. It’s breathable and very waterproof, which makes it perfect.

waterproof paint on an old exterior wall

Leigh Burton

This was the first time using Wethertex ap77. I was struck by the rich matt finish! We needed a product that was breathable, waterproof and has high adhesion (we used the wethertex silicone stabiliser on all masonry repairs) as previous retail coating was peeling and flaking and trapping in moisture!

Using a silicone-based paint like this means my client will avoid future problems caused by water.

Click here to see more of my work

Waterproof masonry paint on a house

Mike Cupit

We used Emperor Paint Masonry Paint on this house. Mostly because the previous paint had failed badly due to moisture being trapped inside the wall. Also, the bricks around the front door had all blown because of water damage over time.

We needed a waterproof paint that would keep the wall dry and not trap moisture. Plus, something we thought would last; it was only painted 3 years previous, so my client was keen for us to take measures for it to last longer this time around.

Emperor Paint is expensive, but it’s an easy sell on a job like this. My client pays a little more, but the paint is very waterproof, and the job will stay looking mint for longer.

the best paint to keep a wall dry

Updated Jun 6, 2024 | Posted Oct 11, 2023 | 0 comments

About the Author

About the Author

Mike Cupit has been in the decorating industry since 2002 and has mostly worked as a Trade Decorator in the domestic sector (peoples’ homes). Self-proclaimed “product geek”, Mike has a passion for paint and decorating tools. Mike now spends most of his time testing paint products and tools, comparing them to similar products on the market, and blogging about the industry in general.
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