Tanking basement walls

basement-waterproofing

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A Guide to Tanking Basement & Cellar Walls

Our guide to tanking basement and cellar walls will provide all the information you need to protect your underground space from damp problems, leaks, and flooding.

If you have a damp basement or cellar and think that tanking might be the solution you require, get in touch with Rentokil Property Care today by clicking the contact us button below or call us on 0800 0121 437 .

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What Does Tanking Walls Mean?

Tanking is the application of a cementitious waterproof coating, commonly known as tanking slurry, to the walls and floor. You will often find that this slurry is supported by the installation of waterproof membranes to ensure complete protection and make sure your basement walls remain dry.

Tanking is primarily used to tackle water ingress, and basement tanking is particularly good at resisting hydrostatic pressure i.e. water pressure on underground walls from the surrounding earth. This has made tanking an extremely popular method of treating and waterproofing damp walls underground.

Tanking Slurry

Tanking slurry is a specially formulated mixture of cement, aggregates and chemical modifiers. These ingredients work together to stop any water ingress from earth retaining walls.

When the slurry dries it forms a smooth waterproof barrier that will prevent water ingress and the various damp problems that can arise as a result.

Tanking slurry still remains permeable to water vapour despite blocking water ingress, and this is what allows any trapped moisture on your walls, like condensation, to escape - essentially making your basement or cellar breathable. This is what makes a tanking system both waterproof and damp proof.

A tanking solution fitted by Rentokil Property Care will fulfil the criteria set out by the British Standards Institute BS 1881, part 122. These BSI waterproofing standards outline best practice in our industry and this attention to quality is what you can expect from our professional team.

Using Slurry to Tank Basements and Cellars

When people are thinking of tanking their basement or cellar they often wonder if they need to wait until the walls have dried up first. In actual fact tanking slurry is designed so that it can even be applied directly to wet walls to begin the process.

When tanking basements our experts apply a minimum of two coats or more depending on the circumstances. The first of which needs to be applied horizontally to the wall and should go down to the wall-floor joint. Tanking should be touch dry and able to support a second coat within 24 hours.

If you are going to leave the tanking exposed for a while before applying a finish, you should apply an extra splatter coat to ensure an adequate key before rendering.

The professional waterproofing experts at Rentokil Property Care have a wealth of experience when it comes to applying tanking solutions and plenty of experience repairing basement and cellar tanking systems that have gone wrong. If you want professional help and advice when it comes to tanking your basement our team are ready to take your call.

What is Tanking Membrane?

Tanking membrane is essentially a studded sheet of damp proof plastic that will manage any water ingress into foundations, basements and cellars.

The studs raise the membrane from the wall and channel any water ingress into an appropriate drainage channel and away from the property. Alongside basement and cellar waterproofing, tanking membranes can also be used in commercial premises to waterproof floors, crawlspaces, storage areas and tunnels.

Applying Tanking Membrane to Basement and Cellars

Once the area is prepared by removing damaged plaster and treating moulds, fungus or other contaminants where appropriate, our technicians will fit the tanking membrane against the wall and drill specially designed studs that will hold fixings that secure the membrane to the wall. When fixing the membrane the sheets will overlap and joints need to be sealed with waterproof tape to avoid any gaps.

Best of all, if you are considering a basement conversion, the tanking membrane can have render or plaster finishes applied directly to it or it can be used behind false walls or galvanised steel trunking.

Tanking membrane will typically work in conjunction with drainage channels and a sump pump to form what is known as a Type C waterproofing system.

When Tanking Walls is Not Enough

Tanking walls in basements and cellars alone is often not robust enough to stop water ingress, damp, and mould permeating your underground space.

This is due to certain conditions such as:

  • Subsidence causing cracks and fissures in the wall
  • Nearby trains or heavy vehicles on busy roads created repeated and mounting vibrations
  • A build-up of hydrostatic pressure behind the earth-retaining wall
  • The building is in an area susceptible to flooding


Typically to rectify these issues a more comprehensive form of waterproofing consisting of a combination of tanking, damp proof membranes and a drainage and pumping system may be necessary.

In such cases, we would recommend that you consult with a professional and qualified tanking specialist to conduct a survey on the property and determine the correct tanking or waterproofing system required to safely ensure the room remains dry and safe.

How Much Does it Cost to Tank a Basement or Cellar?

The cost of tanking your underground space will be determined by

  • How large the space is
  • The extent of damage to underground walls
  • The method of waterproofing or tanking required

Ultimately, it is impossible to give an accurate estimate of costs until a thorough site survey has taken place.

Whilst there will be an initial survey fee, this pales in comparison to the potential costs encountered by installing an inefficient basement tanking solution that causes your underground space and all of its new contents to become saturated with damp, mould and fungus.

Contact the basement and cellar tanking specialists

At Rentokil Property Care our specialists have the qualifications, training and experience to properly install a tanking membrane solution to your basement or cellar.

You can contact our expert team at Rentokil Property Care today on 0800 0121 437 or click the button below to fill in a quick contact form and we will get back to you.

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