Ensuring waterproofing is efficient with a long-lasting tanking installation

When creating a basement space or embarking on a dream basement conversion, water is the big potential enemy, so it’s vital to ensure an effective waterproofing system is installed. Methods include cavity drainage systems, sump and pumps systems and cementitious systems commonly referred to as tanking.

Each basement will require a specific waterproofing and tanking installation, so it’s important the project is assessed and installed properly by structural waterproofing experts to ensure the best solution is determined and the property is protected in the future.

The importance of the right structural waterproofing method

When installing basement tanking systems a key element is that the waterproofing contractors work to BS8102 industry regulation standards (see below) and are part of the project from design through to installation and after care sump and pump servicing.

This is because the choice and installation of a waterproofing system is the vital element to provide protection to a property since water and even mild moisture over a period can wreak havoc with buildings of any kind – especially basements.

Underground spaces face a constant water threat in that the structure is always in contact with the surrounding, porous earth. If drainage is naturally poor or there’s a high-water table, the basement will be surrounded by permanent moisture, and sometimes a lot of it.

This means that the property is not only at risk from ongoing damp conditions which overtime will penetrate through and appear as damp patches on walls but even more destructive is the risk of flooding to the property if water is not controlled and moved away from the property.

Cavity Drainage Waterproofing and Tanking (cementitious waterproofing)

There is a basic difference between cavity drainage waterproofing and cementitious tanking:

Cavity Drainage Waterproofing – includes the installation of waterproof membranes with sump and pumps and drainage channels to control water ingress.

Combined, this provides a cavity drain system the purpose of which is to control water ingress and route water away from the structure.

Cementitious Tanking – is the application of a cementitious coating to the inside of the basement to prevent water entering from the outside; it essentially makes the area watertight.

This tanking method allows for a cementitious (cement-based) mix applied to the walls and ceilings, designed to prevent water penetrating the inside.

These cementitious tanking solutions are classed as ‘Type A’ waterproofing systems in that they create a barrier to water penetration but don’t remove it. Cavity drainage waterproofing is classed as ‘Type C’ whereby water is removed away from the property. Systems and can of course be used in conjunction.

Both methods will allow for a smooth interior surface finish so can provide the opportunity for the interior decoration that is the finishing element to a basement conversion, but it is what has been installed behind the scenes that will decide the future success of the project.

Getting the best cavity drainage and tanking job done

As mentioned earlier, careful assessment to provide the right design and determine the best waterproofing and tanking solution is vital, as is the installation and after care plan itself. It’s important to follow industry standards to support this.

BS8102 regulation standards

The above is the accepted standard for below ground structures as laid down by the British Standards Institute Code of Practice.

Using waterproofing contractors and installers who adhere to BS8102:2009, is a reassurance that they follow best practices when implementing measures to deal with and prevent water entry from the surrounding earth in a below ground level structure – such as a basement or similar.

Waterproofing expertise mandatory in design

If designing a basement conversion, the latest amendment to BS8102 recommends a waterproofing expert be part of the design team working alongside the architect, engineer and builder.


What a basement tanking system is, how it differs from general waterproofing, and the importance of having the right type professionally installed to BS8102 standard.