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How to Waterproof Concrete

Concrete is one of the most used materials within the construction industry. In the 1960s, one of the biggest architectural trends was flat concrete exteriors. Trends come and go and whilst it’s now uncommon to see big concrete buildings being newly built, concrete is still widely used in house foundations and the construction of basements.

In the UK, basements are not a typical feature of new-build houses. They are most commonly associated with older homes in big cities where space is at a premium. Nowadays, lots of basements are transformed into flats or apartments, but where they are still part of the original property, they are frequently used as additional luxury living space.

If you have a home that has a basement and you’re looking to turn it into something unique like a games room, playroom or cinema room, you’ll first need to look into whether your basement is waterproof.

Common Basement Issues 

One of the biggest problems basements have is with damp. In the UK, the soil underneath properties can be very wet – especially in coastal locations. Pair this with the fact most basements in the UK are not new and, when they were constructed, little thought was given to dampness – it’s clear to see why this is an issue that affects a lot of basements.

Signs you have a damp basement include:

  • A musty smell
  • Wet walls/floors
  • Cracks in the walls/floors
  • Mould on the walls/floors

If your basement has any of these symptoms, it’s highly unlikely that you’ll be able to use it for anything – let alone a luxury living area – until you deal with the damp problem.

To resolve moisture issues within a basement, you need to instigate a basement tanking process. This is because there is a high chance that your old basement walls are made of porous brick. They might’ve had a layer of concrete render applied over the top, but unless it was waterproofed, you stand a high chance of falling victim to damp issues.

Can You Waterproof Concrete?

In its natural state, concrete is not waterproof. Instead, it is porous like a sponge, only denser. This means if you construct a cellar or a basement using standard cement mix, it will soak up a percentage of the water from the surrounding earth. This is because concrete is made from cement which is a mixture of aggregates like sand and gravel. The aggregates are mixed with water to form concrete. As the concrete dries the water evaporates, but as it does so, air fills the small pockets and crevices where the water formerly was. This is what makes the concrete porous.

Over time, water will seep through the crevices and begin to diminish the integrity of the concrete. Segments will get damp and chip off, making way for more water and moisture to seep in, causing further damage as it does so.

Luckily, concrete waterproofing is an option and will protect your property from damp and mildew.

How to Waterproof Concrete 

There are a number of ways concrete can be made waterproof, with many people turning to things like waterproof concrete sealer solutions. Depending on the area your concrete is in, this could be a good solution, but it’s not good enough by itself for basements and cellars. Instead, the waterproof sealer is often used on garage floors and concrete patios above ground.

Film-forming sealers utilise a layer of acrylic or epoxy to form a waterproof layer on top of the concrete. It typically has a shiny, glossy finish, but it does wear off quickly so needs to be re-applied frequently. What’s more, this doesn’t stop moisture from forming beneath the concrete getting through and degrading the quality of the concrete from below.

The other option is a penetrating sealer which, as the name suggests, penetrates the concrete and fills the air pockets with silicates. Unlike its film-forming counterpart, penetrating sealer doesn’t change the appearance of concrete and can last a considerably longer amount of time.

Whether or not sealers will be a good option for your property will depend on the area your concrete is in, but in the case of basements, we always recommend basement tanking.

Types of Basement Tanking

Here at Garratt’s Damp & Timber, we offer two types of basement tanking: BS:8102/2009 Type A and Type C. Type A is the more common solution and involves taking the walls of the basement back to their original state. Once stripped, a splatter coat of cement and sand will be applied. This is then followed by multiple coats of render. We do not have a standard render and instead use a mixture based on the individual needs of the property. Other applied barrier membranes are often used too.

Once applied, Type A can be left as is, or you can apply a skimmed coat of plaster to it. Type A waterproofing is most suited towards basements that are in areas without high levels of groundwater. This is because it stops surrounding moisture seeping through to the front of the basement walls, but it doesn’t extend further than this.

If your basement walls have already been degraded by damp, or if your property sits in a particularly damp area with higher levels of sitting groundwater, we recommend Type C tanking. This type is more rigorous and involves ridding the basement walls, ceiling and floor of any loose sediment. Next, a cavity drainage membrane is installed across the walls, ceiling and floor, with all plumbing and pipework sealed into the membrane. A sump and pump system is then installed via perimeter channels around the walls and floor. This carries excess water away from your property and into the drain, ensuring no water enters your basement.

Waterproof Your Concrete Basement 

Find out more about waterproofing concrete floor and basements by calling us on 0208 535 7536. Alternatively, contact us online to arrange a free site survey during which we will assess your property and determine the best solution for you.

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4:04 PM Sep 22nd|@garrattsdamp
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