Do you want to convert your cellar into a functional room in your home? If so, it is essential that your cellar is waterproof. Cellars will often lie below a “perched water table”; this means water may saturate the ground at a higher level than normal, before sinking down to the true ‘water table’, at a lower level. This ‘perched’ effect can cause many cellars to suffer from hydrostatic pressure.

When hydrostatic pressure builds against the cellar wall, masonry and brickwork will crack and leaks will cause water will flow into the cellar and even small volumes of water will cause the cellar to become a damp, dank and dingy part of your home.

Damp conditions are a serious threat to health of any room on the home as they can allow problems like dry rot and wet rot to thrive and they attract household pests. This is the last thing anyone would want to happen to their newly converted cellar.

How to waterproof a cellar

There are a few ways to waterproof a cellar, and these options vary from traditional to modern techniques. In a lot of cellars you will find that a traditional method of waterproofing like cementitious tanking or an external drainage system like a French drain has already been installed but has degraded over time.

Regardless of the reason your cellar needs waterproofing there are two main ways you can approach a retrofit solution:

Tanking a cellar

Cellars are traditionally waterproofed by applying a cementitious layer to the walls. This barrier of waterproof cement, known as tanking, creates a barrier that does not allow any water ingress to seep into the cellar. This is a perfectly fine way to waterproof a cellar in many cases but if your property is susceptible to vibrations in the surrounding earth, or extreme hydrostatic pressure cause by excess moisture in the soil around the cellar, then tanking may eventually crack and leak over time.

You can find out more about this process on our tanking a cellar web page.

Installing a cellar waterproofing system

A modern cellar waterproofing system is a completely different concept to a traditional system like tanking. Where a cementitious coating of the cellar wall will create a barrier to stop water from entering the cellar, a modern cellar waterproofing system will allow water ingress but channel it, drain it and pump it away safely and hidden from view.

By controlling the water ingress “behind the scenes” and channelling it away these systems are less at risk from the cracks and leaks caused by hydrostatic pressure and are also easier to maintain.


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