Finding the Best Waterproofing Coating

What Is A Waterproofing Coating?

Let's firstly tackle the question of what exactly is a waterproofing coating? The term waterproof refers to the ability of a coating to prevent the ingress of moisture. Many paints on the market today refer to themselves as weather protective or weather resistant, which generally means they offer some protection from moisture, but do not prevent the ingress completely. To be completely waterproof, a coating or paint must be water repellent, or hydrophobic, which means that the water is more attracted to itself than the waterproof coating, which means it forms beads on the surface that run straight off. This can be seen in a number of man-made and naturally occurring materials, such as glass & the lotus leaf.

What Is Breathability?

So, to be considered waterproof, it is crucial that the coating is hydrophobic, which will repel any moisture that lands on it. However, this can create a significant problem. If a waterproofing coating is not is not breathable, it will prevent moisture from escaping the treated surface. This is the case with many 'sealers' that create a waterproof film on exterior surfaces that will create a complete moisture barrier. When moisture from inside the property builds up, it cannot freely pass through this film, causing it to blow the waterproof coating off the surface or even worse, causes the build up of moisture to cause significant damp problems.

Why Use a Waterproofing Coating?

You may be wondering why you would use a waterproofer, if some of these products can cause significant problems?

1. Damp

As we have mentioned, building materials such as brickwork, stone & render are porous, meaning that they soak up moisture. This moisture can then travel from the external wall to the internal wall in both solid wall & cavity wall properties., eventually causing damp problems.

2. Damage

Another key reason why waterproofing exterior walls is crucial is to prevent the long-term deterioration in the building materials. When a crack appears, water can enter the crack and be held within the wall. As water freezes it has an expansion rate of 9%, which means each time the moisture freezes and then thaws, it causes the crack to increase in size. This then allows even more water the penetrate and the cycle continues, until the brickwork, render or paintwork fails, causing significant damage, or in the best-case scenario will cause the paintwork to peel, if the exterior wall is painted.

3. Long-term performance

This is why many standard masonry paint that do not offer waterproof protection are not long lasting products. The moisture causes them to deteriorate in a matter of years, which is why our experts would always recommend opting for a waterproof coating is you are planning anything other than a small-scale project.

4. Heat retention

Wet walls mean cold walls, as moisture creates a thermal bridge that allows heat to escape from a property much quicker than a dry exterior walls. This is why waterproof coatings have been shown to prevent heat loss and reduce energy bills for homeowners.

The Best Waterproofing Coatings

Waterproof coatings are designed for a range of surfaces, including exterior walls, wood & roofs. Here are our picks for the best waterproofing coatings currently in the UK:

Exterior Walls

Masonry Cream

The best waterproofing solution for bare brickwork is a masonry cream. This is a clear solution that chemically bonds to the brickwork, waterproofing the brick itself rather than forming a waterproof surface on the brick.

Emperor Masonry Creme in particular maintains almost complete breathability while preventing moisture absorption by 96.3%. By creating a waterproof but breathable protection on masonry, the masonry cream significantly reduces penetrating damp & has been proven to keep treated surfaces 6°C warmer on average.

Emperor Masonry Creme comes has undergone independent tests that showed no signs of deterioration in appearance of performance after a 25 year weathering test, which is why Emperor Paint offer a lifetime guarantee on the product.

• Can be applied to brick, stone, mortar, cement or sandstone
• Offers invisible waterproof protection
• Proven 25 year performance
• Prevents penetrating damp
• One coat application

Masonry Paint

You may want to refresh your home's exterior with a fresh new colour, which is where masonry paint is a great option. Emperor Paint have a coloured exterior paint that offers the exact same waterproof protection as their masonry cream, but in a coloured paint. As we have mentioned, the most common cause of exterior paint failure is moisture, which gets behind the paint and causes it to peel and flake off the exterior wall. By preventing the water ingress, Emperor Masonry Paint has been proven to not alter in appearance of performance for at least 25 years, and comes with a lifetime guarantee, just like its clear version.

The other big advantage of a waterproof paint is that it is self-cleaning. By repelling moisture, it also repels dirt and grime, plus it does not allow moss to attach itself to the exterior wall. This means that when it rains, any dirt simply washes straight off the wall, leaving them looking new & pristine for years. For this reason, waterproof masonry paint is fast becoming the go-to exterior paint for decorators and homeowners alike.

It is available in 12 popular standard shades, including white, off-white & light grey.

• Can be applied to brick, stone or render
• Contains the most advanced super hydrophobic technology
• Self-cleaning
• Proven 25 year performance

Exterior Wood

Wood treatments

Just like paints & coatings for exterior walls, there are a number of products on the market that are designed to provide long-lasting waterproof protection to exterior wood. When it comes to a coloured wood paint, there are two stand out options available in the UK:

1. Dulux Trade Ultimate Opaque

Dulux Trade Ultimate Opaque is an oil-based exterior coating that creates a water-repellent matt finish on exterior wood. This weather protection gives it a fantastic 10 year durability, keeping hardwoods and softwoods alike protected from the elements.

Aside from its performance, it provides a beautiful opaque coloured finish, that is available in any colour you want. This is because Dulux Trade Ultimate Opaque is one of the many colour match paints that can be mixed in any RAL, British Standard or NCS shade, plus equivalent shades of all other paint manufacturers, including designer shades.

While it is more expensive than other water repellent wood coatings, it does provide you with the ability to get a custom mixed colour, plus with a 10-year lifespan, it represents excellent value for money.

• Can be mixed in any colour
• 10-year weathershield protection
• Breathable
• Suitable for doors, windows & other joinery
• Oil-based
• Matt finish

2. Crown Trade Flexarb

Crown Trade Flexarb just like Dulux Trade Ultimate Opaque, is a waterproof coating for exterior wood that comes in a solid, opaque coloured finish. While it is cheaper than Ultimate Opaque, it comes with a slightly lower lifespan of 6 years and cannot be mixed in any colour, instead coming in a number of standard colours.

Nevertheless, it is a fantastic waterproof coating that will resist peeling or flaking thanks to its flexible finish that is ideal for all exterior timber, including fences, doors and windows. Furthermore, it is a satin finish paint, which is perfect if you want to achieve a slightly higher sheen.

• Flexible finish
• Breathable
• Resists peeling, blistering & flaking
• Up to 6 years protection
• Comes in a range of standard colours
• Satin finish

Roofs

Roof Repair

A surface that is under continuous stress from the weather is roofs. While there are a number of roof coating products available, these are not DIY friendly, which is why it is always advised that you opt for a professional. One issue that can occur on many properties, especially those with conservatories is leaks on roofs, gutters & chimney stacks. Fillcoat Fibres by Rust-Oleum creates a waterproof barrier that can be applied in spot areas and in all weather. It is a great example of a waterproofing product that can be used in spot areas, rather than the traditional form of waterproofing a full area from water ingress.

• Immediate waterproofing
• Can be applied in all weather conditions
• 1300% elastic

Things To Consider

There are a number of things to consider when deciding what waterproofing solution to use:

1. Long-term performance

With the long-term performance of waterproofing coatings such as Emperor Paint, it is important to remember that they are designed for long-lasting performance. They cannot be simply painted back over easily if you do not like the colour. When you opt for these coatings you are making a long-term decision. Make sure you are happy with the colour you choose by ordering a sample pot first.

2. Sealers

It is hugely crucial to ensure that the waterproofing product you use is breathable. Usually when waterproof paints refer to themselves as a 'sealer' they are not breathable. Ensure you double check before buying to see if there is any mention of this by the manufacturer.

3. Application

As with any decorating project, the results are only as good as the application. It is crucial that you use a fungicidal cleaner, especially when using a coloured system as this is going to prevent on moss growth in the future. If you apply a waterproof coating to a wet or dirty surface, the coating is going to fail. Before application, read the manufacturer's instructions and ensure you are prepared for the project.

How To Apply A Waterproofing Treatment

All waterproof coatings are different, which means there is no one way to apply them all. Having said this, their are some common areas that are useful to know before you begin the project:

1. Check walls for issues - before applying a waterproof treatment, it is crucial that you repair any issues with the surface, such as filling any cracks or removing any peeling paint. As any professional decorator will tell you, the preparation is the most important part of any decorating project.
2. Clean the surface - any dirt or grime is going to significantly reduce the quality of the finish you achieve, and the ability for the product to successfully waterproof your exterior surface. Ensure you clean the surface beforehand using either a simple cleaning solution, or even better an anti-fungal wash that is going to kill any bacteria & growth on the surface. This will prevent any fungus blooming underneath the paint film, which will cause the paint to fail.
   
3. Priming - it is common for a coloured waterproof coating to require a primer before being applied to a bare substrate. This allows the coating to adhere to the surface properly as a bare surface will absorb the paint and result in an uneven finish. A primer is not needed with previously painted surfaces.
4. Application - you can use a roller or a brush to apply most waterproof coatings, which will either require one or two coats. Ensure you apply from the top down for the best finish and do not apply any coloured system in weather warmer than 20 degrees, as the paint will dry too quickly, leaving uneven streaks.
   

Frequently Asked Questions

Q. Can you apply paint over the top of masonry cream?

This is a question we are frequently asked in relation to waterproofing coatings. Due to the water repellent nature of these products, you cannot paint over the top of them as the paint would not adhere. This is often asked as homeowners want to 'seal' their exterior walls from rain water, but want a painted wall. A waterproofing coating does not act in the same way as a primer, which is applied before paint. If you want to apply a waterproofing coating and then a paint, the best way to do this is to simply use a waterproof paint to start with. This will waterproof the wall and provide you with an attractive coloured wall.

Q. Do you need a primer when using a waterproof wood paint?

Any bare timber requires a primer to be applied before you paint it to prevent the paint from absorbing into the surface. This is easy to apply using a brush or roller and only requires one-coat.

Q. Do you need a primer when using a waterproof masonry paint?

Just like bare timber, if you plan to paint a bare brick, stone or concrete exterior wall, you must apply a primer. If the surface has already been painted, you do not need to apply one, simply clean the wall down before painting.

If you are using an exterior wall coating such as waterproof masonry paint, you must ensure you use the correct primer. Using a standard primer can impact the ability for the waterproof paint to perform. For example, Emperor Paint recommend you use their Emperor Masonry Primer with their masonry paint.

Q. How can I tell if a product is waterproof?

A large number of exterior paints & treatments will claim to have some sort of weather protection due to the conditions they must endure. It is important to consider the terminology these products use. To be fully waterproof, a product must be water repellent, which is why if a product says it is weather resistant or weatherproof, this is often a sign that it is not completely waterproof and is simply designed to help protect against the elements.

We hope this has answered any questions you may have had regarding waterproofing coatings. If you would like any more help & advice, our team of experts are on hand. Why not send an email to the team at hello@paintersworld.co.uk or message us on social media? At Painters World we have a wide range of paints & decorating supplies available, so no matter the job, we've got the right tools for you. Plus, get FREE next working day delivery on all orders over £50.