Basement tanking or basement waterproofing – What’s the difference?

Basement waterproofing or basement tanking – Is there a difference?

For property owners who have a basement as part of their property, it can often be the case that it serves as just a dark, musty and unloved storage space, into which you quickly fling any unused household items or Christmas decorations and forget about them for the rest of the year.

However, converting or extending a basement is becoming a popular way to turn these unloved spaces into something extraordinary to create extra living space such as an office, gym, games room, or cinema. The spaces that can be created can look incredible, but this type of building work does not come without risks. Getting right what goes on behind the scenes is the essential element to ensure that the structure has been correctly prepared so it remains dry, damp and water free for the long term. Using experienced basement conversion professionals therefore is a priority so ensure you receive expert advice on the best waterproofing options available and the best installation of the waterproofing system.

It can help to understand the waterproofing jargon and a common question is ‘what is the difference between basement tanking and basement waterproofing?’   The answer is that they are both terms that refer to methods of waterproofing used to keep the basement dry but there are differences with regards to the type of waterproofing method used. If you are considering a basement conversion, it can be helpful to understand them in the context of the various materials and techniques that can be used to protect a structure from water ingress so the following is a guide to help.

Basement Waterproofing (using cavity drainage)

Cavity drainage basement waterproofing is the installation of a ‘type C’ cavity drain system that drains away water that is at risk of seeping into the basement and pumps it away from the property.

Comprising of waterproof membranes, drainage channels, sumps and pumps and alarms – cavity drain systems are designed to manage any water entering the property and remove it safely so it does not penetrate into the property.

Hidden drainage systems in conjunction with high quality pumps and structural waterproofing membranes and alarms that alert when there is a build-up of water in the system, work together to manage the build-up of ground water around the basement and lower the pressure build up on the walls. The results are a dry basement that when converted will continue to work behind the scenes to keep the basement dry.

Basement Tanking (cementitious tanking)

Basement tanking tends to refer to a waterproofing system that uses a waterproofing ‘barrier’ applied to the necessary surfaces such as walls, roof and base slabs.

These barriers can be applied in the form of a special coating or cementitious membrane as it can also be known, to make the basement impermeable to water ingress. A common material used for this is a ‘tanking slurry’ which is a liquid, waterproof coating that when applied to surfaces creates an impermeable, watertight barrier to prevent issues from water ingress occurring.

There are occasions in which basement tanking using a cementitious membrane is not suitable. Some basement tanking systems in London for example can run into complications due to the proximity of the property to underground or over ground train lines.

Under certain conditions, this tanking method can therefore be susceptible to cracking which is why it may not be an appropriate solution for;

  • New builds (due to expected ‘settlement that occurs)
  • Properties with subsidence
  • Properties near railway lines or busy roads (due to vibrations)

In these circumstances if tanking is not an option or if previous tanking measures have failed then other basement waterproofing methods can offer viable solutions that are more likely to be successful. Sometimes a combination of both is appropriate.

The choice of the right basement waterproofing method is complex. British Standards 8102now recommends that a Waterproofing Specialist is part of the initial design team, working alongside the architect and builder right at the start of the design phase.  The key to keeping a basement dry, whether it’s a basement renovation, conversion or extension, is to do your research and use experienced professional basement waterproofing contractors that you can trust to do the job right.