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Below Ground waterproofing upstand and slab

Tony C

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Hello fellow self-builders,


I am currently in the process of waterproofing a below-ground concrete slab and upstand (Its below ground about 600mm) , with the added requirement of fixing a timber frame hold strap on the slab. I've reached out to RIW, and they recommended their Toughseal, a 2-pack resin system liquid DPM. However, the cost is a bit steep at £27/m2.

The construction of the slab and upstand is in good standard, and there is currently no visible water ingress. There's a slight dampness in some areas, but nothing alarming. I'm curious if any of you have dealt with a similar construction and have successfully used an alternative, more cost-effective product for waterproofing.


Thank you in advance for your time and assistance!

RIW below ground waterproof recommendation .png

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Can you put a membrane and drain on the outside or is no access possible? 


It usually isn't good practise to seal from the inside because if the wall does get saturated then water will, eventually, find a way through. An internal drained membraned would be another option if the levels worked out. 

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Thanks George,

Unfortunately there is no access on outside.

I also have a basement where I am planning using Delta system as you suggest.

But I am looking for a internal solution for this a little below ground slab.


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