Christopher Fletcher, Technical Services Chemist at Thompson’s, explores the damage driving rain can cause and how correctly sealing brickwork can help provide a line of defence.
No one likes the rain – it makes everyday tasks more difficult and inconvenient. But what about its impact on a home? And how can you fight against the effects of driving rain?
It’s no secret that the UK is accustomed to heavy rainfall. In fact, Autumn 2022 was wetter than average, with the year recording an average rainfall of 1,051mm¹. This isn’t likely to change anytime soon, with extreme weather conditions (such as floods and storms) being linked to the effects of climate change and global warming.
With this in mind, it’s no surprise that moisture damage or having water appear inside the four walls of your home is every homeowner’s worst nightmare. Yet, with most houses constructed from porous materials, such as brick, concrete or stone, it is a real risk. Moisture is the most natural agent responsible for the deterioration of a building’s exterior, with the amount of water deposited on outside walls by driving rain larger than any other source, including condensation.
Defined as rain propelled by driving wind, driving rain can result in significant damage to a home, including staining, leakage, dimension change and much more. Without the correct protection, it’s possible for rain to seep through exterior walls, making its presence known through the appearance of damp patches, crumbling plaster or peeling wallpaper – a process called penetrating damp. The situation can also get worse in the colder winter months, with the potential for freeze thaw damage. This is when moisture soaks into the brick or stonework during the day, freezes at night (expanding as a result) and then thaws in the morning sunshine, before the whole cycle repeats.
While two of the first means of defence against rain entering a home are, of course, a leak-free roof and correctly performing gutters, in heavy winds even this is not enough to prevent driving rain from reaching the exterior walls. If a customer is concerned about penetrating damp or freeze-thaw damage affecting their home, recommend that they take action by sealing the external brickwork.
While there are various products available on the market, look out for one that is quick drying and is able to be applied to damp surfaces, meaning you don’t have to wait for the last rainfall to dry before starting work.
As with most jobs, preparation is key. First, give the surface a good scrub with a stiff bristle brush to remove any dirt, moss or other debris, as they can affect the sealant’s ability to properly adhere and soak into the substrate. This is also a good time to fill in any cracks and carry out pointing repairs, if required.
Water sealant is often best applied with a brush or roller, especially if you’re working with a large area. If you’re tackling a wall, work in one metre sections from the bottom upwards and ensure an area is fully saturated (including the mortar lines) before moving onto the next section. Make sure to treat the whole wall rather than isolated areas, otherwise you can unknowingly create weak points, and always ensure the first coat has fully soaked in before applying the second.
Thompson’s Water Seal uses a unique micro silicone emulsion to help stop water in its tracks and is suitable for use on brick, concrete and stone. Providing long-lasting waterproof protection, including preventing freeze-thaw damage, Water Seal is easy to apply with a dry time of just two hours and has low VOC content.
Alternatively, for jobs where time is tight, there’s also Thompson’s One Coat Water Seal.
For more information on Thompson’s One Coat Water Seal visit Water Seal for Waterproofing | | Thompson’s Weatherpoofing (thompsonsweatherproofing.co.uk).
¹ Met Office – UK Climate Summary 2022
