Waterproofing Walls

The Importance Of Waterproofing Walls

Many homeowners are under the impression that their exterior walls, be it brick, stone or render, are waterproof. This contrary to popular belief is not the case, as these mineral surfaces are actually porous, meaning they can uptake water. The more porous a material, the more water it can absorb.

When this moisture absorbs into the exterior walls of a property, it can lead to a number of problems.

Damage

The main issue relates to damage, as the moisture can expand within the exterior wall. When the moisture that has absorbed into the wall undergoes a freeze-thaw-cycle when temperatures drop, it expands, causing render, brick or stone to crack under the movement. These cracks then allow more moisture to enter the wall, creating a cycle of further damage.

Any moisture content within exterior walls can also lead to mortar crumbling, brick faces spalling & other damage related to consistent exposure to high moisture conditions. Rendered properties are particularly prone to damage as any moisture that finds its way behind the render can cause large cracks to open up on the face of the render.

Damp

Whether you have a cavity wall or a solid wall property, penetrating damp can be a huge problem. Penetrating damp is caused by moisture ingress through an exterior wall of a property into the interior wall. Unlike rising damp, which is caused by moisture transferring from the ground, penetrating damp can occur at any level of the building.

Properties with a solid wall construction are particularly susceptible to penetrating damp as they do not have a cavity. This cavity acts as a barrier between the exterior and interior structure, reducing the ability for external walls to transfer moisture to internal walls. Without a barrier, solid wall structures allow any moisture than absorbs into porous external walls to travel through to the internal walls, causing damp & mould problems.

While properties with a cavity wall are designed to prevent this transfer of moisture, this is not always the case. This is because wall cavities can become blocked by debris or poorly fitted insulation, which recreates the bridge for moisture to transfer from the external wall to the internal wall.

Discolouration

As with any mineral surface, moisture will create the ideal conditions for moss, lichens & other fungal growth to develop. Over time, the walls will also begin to discolour where the moisture darkens the surface.

Heat Retention

Damp content of 5% can lower the insulation properties of a surface by 50%. Wet walls mean cold walls, as moisture creates a thermal bridge that allows heat to escape from a property much quicker than a dry walls.

Signs Of Water Ingress

There are a number of things that can indicate whether your exterior walls are susceptible to water ingress:

• Damaged brickwork - any cracks, spalling brick faces and crumbling mortar can all be caused by high levels of moisture.
• Internal damp & mould - damp patches on internal walls, especially when they appear higher up the walls are key indicators of penetrating damp.
• Dark patches - dark patches on external walls is one of the strongest indications of water ingress. These can appear at any level of the building and gather on those walls that are most vulnerable to wind-driven rain.
• Peeling paintwork - if your external walls are suffering from blistering and peeling paint, this is a good indication that there is a moisture issue. This is because water is the most common cause of paint failure, along with poor preparation.
• Efflorescence - if you have never heard of the term efflorescence, the chances are you are familiar with the sight of it. Efflorescence is a white, powdery substance that is left on exterior walls, caused by salt deposits being drawn out of brickwork when water that has gathered in the wall evaporates. Although not dangerous, it can be a real-eye sore and is a strong indicator that there is a moisture problem.

Waterproofing Treatments

If you have identified that you are suffering the water ingress on your exterior walls, you may be wondering what waterproofing products are available in order to prevent your exterior walls from absorbing water.

It is crucial to know that no matter what waterproofing product you opt for, it must be breathable. Breathability refers to the ability for a surface to allow water vapour to freely travel through. If a waterproof treatment is not is not breathable, it will prevent water vapour that naturally gathers inside a property or any moisture that finds its way through cracks in the wall from escaping the treated surface. Eventually, any trapped moisture will continue to gather until it breaks through the waterproof coating. This is after it has caused significant damp & damage. A coating is considered breathable if it has an SD value of below 0.5. If you cannot find the SD value of a product, the chances are that it isn't breathable.

This is the case with 'sealers', which are waterproof products that create a waterproof film on exterior surfaces. While offering waterproof protection, by creating a non-breathable coating on the wall, any moisture simply gathers inside the wall. These sealers will eventually fail in a matter of years once any damp problems have been worsened.

There are two forms of highly breathable waterproofing products on the market in the UK. These come in the form of waterproof masonry paint & masonry cream.

Waterproof Masonry Paint

Waterproof masonry paint is a form of exterior paint that is specially designed for use on external brick, stone, concrete or render. You may be wondering why all masonry paint isn't waterproof? The truth is, masonry paints are all designed to varying levels of quality and durability. While all masonry paints have some level of weather protection, but this does not make them waterproof. To be waterproof, a masonry paint must be water repellent, which prevents any moisture from absorbing into the surface. For this reason, many masonry paint manufacturers refer to their paint as weatherproof or weather resistant, rather than waterproof or water repellent.

A silicone masonry paint is a form of paint that is water repellent, while also being highly breathable. A standard masonry paint is generally an acrylic-based masonry paint that will uptake some moisture and isn't particularly breathable. For this reason, a standard masonry paint will have a lifespan of 1-10 years while a silicone masonry paint will have a lifespan of 25+ years.

Masonry Cream

Masonry cream is a clear waterproofing treatment for bare brick, stone or concrete. The way that masonry cream works is that it chemically bonds to the mineral surface and slowly penetrates into the surface. This is contrast to a brick sealer that creates a film on the surface of the masonry. The best way to think about masonry cream is that it waterproofs the brick itself, rather than creating a waterproof coating.

For this reason, masonry cream is extremely durable as there is no film to break. While remaining fully breathable, surfaces treated with masonry cream will have water repellent properties that prevent any water absorption.

Emperor Paint

Here at Painters World, we only stock the highest quality products as we believe that a job done right is a job done once. We stock the Emperor Paint range, which includes their masonry paint & masonry cream. Both products contain Emperor Paint's super hydrophobic technology that repels water, preventing 96% of water absorption. Both treatments have also been shown to be highly breathable, with SD values of 0.03 and 0.01 respectively.

In independent testing, Emperor Masonry Paint & Emperor Masonry Creme were put through a 25 year accelerated weathering test to demonstrate the durability of the waterproofing treatments. After 25 years of harsh weathering, both treatments were found to have no change in appearance or performance. For this reason, Emperor Paint offer a lifetime guarantee on all products, ensuring their performance for decades.

In the testing, the treatments were also found to keep a treated wall 6°C warmer on average compared to a wall left untreated.

Emperor Masonry Paint

• Can be applied straight to previously painted brick, stone, concrete or render
• Can be applied to bare brick, stone or concrete when used with Emperor Paint Exterior Masonry Primer
• Ideal when you want to achieve coloured finish
• Super hydrophobic (water repellent)
• Highly breathable - SD value of 0.03
• Comes with a lifetime guarantee
• Independently tested and certified to have a 25 year proven performance in harsh weather conditions
• Silicone-based formulation
• Self-cleaning
• Heat retaining (keeps treated walls 6°C warmer on average)
• Energy saving
• Reduces problems associated with penetrating damp
• Discourages green growth
• Discourages discolouration from constant wetting

Emperor Masonry Creme

• Can be applied to bare brick, stone & concrete
• Super hydrophobic (water repellent)
• Highly breathable - SD value of 0.01
• Does not alter the appearance of masonry, leaving a natural finish with no sheen
• Dirt cannot attach to the wall once the masonry cream is applied, making it self-cleaning
• Heat-retaining (keeps masonry up to 6°C warmer on average)
• Only requires one coat
• Penetrates up to 17mm into the brick or stone for longer lasting performance
• Reduces penetrating damp
• Discourages green growth & discolouration that is caused from constant wetness
• Independently tested and certified to have a 25 year proven performance in harsh weather conditions

How To Waterproof Exterior Walls

What You Will Need:

• Masonry paint or masonry cream
• Primer (if required)
• Filler
• Filling knife
• Paint brush
• Paint roller
• Masking tape

1. Check walls for issues - before applying a waterproofing treatment of any kind, it is crucial that you repair any issues with the surface. Repairing any cracks or removing peeling paint from the surface is crucial before you apply any treatment as the surface must be sound. Apply an exterior filler such as Toupret Fill-Flex Exterior Flexible Filler using a filling knife and leave to dry, before sanding back to a smooth edge. If you are applying masonry cream, you will have to remove all paint from the surface before applying as this is only for bare surfaces. If you cannot remove the paint, you can overcoat this using Emperor Masonry Paint for a painted finish.
2. Clean the surface - any dirt on the surface of exterior walls will significantly reduce the ability for the product to successfully waterproof your walls. 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 is recommended as any fungal growth that is present before you apply your treatment could bloom and cause paint failure if you are using a waterproof masonry paint.
3. Mask - masking up any surfaces you do not want to paint is crucial, as waterproofing products are designed to be tough and durable, making them difficult to remove once applied. Apply a good-quality exterior masking tape to the edges of doors & windows, plus put down a dust sheet on the floor to protect it from paint splatter.
4. Priming - it is common for a coloured waterproof masonry paint to require a primer before being applied to a bare substrate. This is not necessary if you have a very small patch, where you have removed peeling paint for example. On these very small areas, you can apply a coat of the waterproof masonry paint diluted by 10%. On any larger areas, applying a primer 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 a thin, watery substance that can be applied easily using a brush or roller in just one coat. Leave to completely dry before applying the paint. If the surface has been previously painted and the paint is sound, priming is not required.
5. Application - you can use a roller or a brush to apply most waterproofing treatments such as masonry paint and masonry cream. 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. Check weather conditions to make sure there is no chance of rain while you are applying the products, as any rainfall within 2 hours of applying could lead to it washing off.

Frequently Asked Questions

Q. Are the treatments only for exterior use?

Yes, due to the rainfall exterior surfaces must endure, a waterproofing treatment is only designed for exterior use. That does not mean that there is not internal forms of moisture that can be protected from. Condensation in rooms such as kitchens and bathrooms can build up, leading to internal mould growth. An anti-condensation paint such as Suretherm Anti Condensation Paint will stop mould from gathering on these internal walls by preventing condensation from forming. It is important to identify whether the mould is caused from internal or external moisture. If it is gathering on an external facing wall, the likelihood is that this is caused from penetrating damp. If the mould is in a bathroom or in a room that is not external facing, this could be condensation.

Q. What colours of Emperor Masonry Paint are available?

Emperor Masonry Paint comes in 12 standard colours, which include white, off-white, light grey and a number of other light & pastel shades.

We hope this has answered any questions you may have had regarding waterproofing walls. 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.