Technicians carrying out tanking works

How to Waterproof Foundation Walls?

5 October 2021

It’s no secret that property is amongst some of the most expensive purchases and investments you can make in your life. So, taking the steps to ensure that your property is secured against potential damage from flooding and other forms of water damage is an important one.

Not only that, but ensuring your foundations are protected against water damage is a legal obligation, adhering to BS8102: 2009, the British standard when it comes to waterproofing in British properties.

You may have already considered the importance and steps needed to make your below ground structure more secure against the problems associated with water damage. But, in case you are still wondering, or you need some further information, this article will run through the fundamentals of foundation waterproofing and what you might need to install in order to be up to British Standards.

What Is Foundation Waterproofing?

First off, let’s talk about what foundation waterproofing is, and why your property is going to need it. Right away, lets go back to BS8102: 2009, that British waterproofing standard we mentioned before. You can read more about it here, but the crux of the matter is this: BS8102: 2009 was written and put into place to help properties retain their structural integrity and fend off water-based damage for an extended period of time.

So, what kind of waterproofing, if any, is specified for basements in BS8102: 2009? Well, the regulations laid down in BS:8102 stipulate that earth retaining structures (like building foundations and below ground structures such as basements) are protected by at least two of the three recognised types of waterproofing in Britain.

Type A Waterproofing, otherwise known as tanking or barrier protection is the application of a waterproof slurry to either the interior of a below ground property, or to the exterior fixtures of a property that are pressed against the earth directly – such as a basement or foundations.

Type B Waterproofing is a process in which the foundations themselves are constructed from a waterproof material, most commonly concrete.

Type C Waterproofing involves an internal cavity protection system, made up of a waterproof membrane that lines the interior of a basement so that any water ingress is captured, collected and drained via basement floor drainage safely. Alternatively, you can make use of external cavity drainage channels.

How Are Building Foundations Made Waterproof?


Realistically, the waterproofing of your properties foundations is a task that you will hopefully never have to contend with. This being because when properties are initially constructed their waterproofing systems should already be in place.

However, in some older properties, you may find that the waterproofing that has been installed isn’t fit for purpose, or that what has been installed Is now failing and you have flood or subsidence to deal with as a result.

In this situation, we cannot stress enough how your first step should be to call out professionals. Waterproofing a properties foundations, be they a foundation wall or foundations alone, is a task that should only be completed by an experienced and qualified waterproofing design specialist. You can find them within our team at Timberwise. Call 0800 288 8660 to talk to us today before you go any further.

So, the very first step in waterproofing any building’s foundations is going to be having a survey conducted to establish precisely what your properties foundations needs are regarding waterproofing. It might be that you need two separate forms of waterproofing fitted as per BS:8102 guidelines, or it could be that you only need one additional form of waterproofing installed so that you can be brought up to the standards of the code.

Either way, a survey will let you know what waterproofing work will need to be completed, and there are one of three options. The first option is that both a Type A and a Type C waterproofing system need to be installed, as your property needs two new forms of waterproofing installed.

The other two options are having either a Type A or Type C waterproofing system installed as your property already has one of the three different waterproofing systems in place.

Why not Type B waterproofing as an option though? Well, as previously mentioned, Type B waterproofing is a system that relies on the materials of the building itself being waterproof. It is near impossible (or incredibly expensive) for foundations to be replaced with all new waterproof materials.

Type A Foundation Waterproofing

Man applying slurry to a basement wall from a bucket

So, in the case of Type A Waterproofing, it will need to be decided if your foundations require external application, or internal application. In the event that external application to your foundations is needed, then it will be required for your property to have the area around the foundations excavated so that the slurry can be applied to your property, thus making it waterproof.

This is lengthy process as you might imagine, especially with excavation involved. If you are aiming to completely waterproof your below ground structure as well as the foundations themselves, then you might find that Type A Waterproofing can be applied to the interior of your foundation walls as well, as a form of barrier protection or ‘tanking’ solution.

This is only one form of waterproofing though. It might be that you need to employ another in order to bring your building in line with BS:8102.

Foundation Waterproofing Drainage

One consistent problem that waterproofing technicians have to deal with when installing waterproofing measures is the safe disposal and drainage of water that would have otherwise affected your property.

In the case of internal waterproofing, for example in the installation of a Type C Waterproofing system on the interior of a basement, it’s easy to direct collected water into a sump pump that can safely channel away any water.

However, on external; waterproofing measures it can be a little more complicated. A common course of action is for a French drain, or a land drain, to be installed at the foundation layer (pointed downwards) so that the collected water can be collected and drained away safely.

In the case of Type A Waterproofing systems applied to foundation walls, the French drain will run around the entirety of the foundations themselves, so that any water repelled by the slurry can be collected.

Why Do I Need Foundation Waterproofing?

With all that in mind, you might be wondering why foundation waterproofing is so important. One reason is that if your properties foundations are damaged then you might experience subsidence, where your property can literally sink into the ground – and that comes with a hefty price tag attached to it when it comes to repair.

That’s just one of the many structural based issues that can spring out of unprotected foundations. Another much more likely and as potentially equally devastating is the possibility that lax foundation waterproofing can lead to catastrophic flooding, and all of the nasty side effects associated with that flood.

This means that your properties foundations could develop damp, black mould and mildew, ultimately reducing the quality in the building materials and comprising your property. There is also the potential for the problem to slowly spread upwards and outwards through your property. That’s not to mention if the foundation walls and basement level walls are actually holding an inhabitable basement – which if flooded could lead to the loss of expensive decorations and personal effects as well as the development of damp and those other horrible side effects we mentioned before.

So, avoid catastrophe, disrepair, and damp, and give Timberwise a call today if you think you could benefit from below ground waterproofing solutions. Our experts can talk you through your properties needs, and following a survey, will be able to provide a tailored solution that can all be installed safely by our waterproofing technicians.

Ring 0800 288 8660 or get in touch online today to get started.