Hi all,
in the middle of renovating our first home. It is a 1960 built ex-local authority semi with felt DPC. Having stripped the kitchen tiles I've found a damp area around the rising main. I removed the red coloured screed and removed the concrete(No obvious DPM) to reveal the incoming water main cased in a 4" ceramic pipe. The clay soil directly beneath the concrete is quite damp.
I have also cut a 30cm wide x 16ft chanel to carry a soil pipe for groundfloor toilet, clay under the chanel also quite damp.

My questions: why is the clay still damp? (having been under the house since 1960)
Is it likely to cause a problem?
Having cut the concrete open how should I re-seal?
Will tanking the floor simply displace/trap the damp in another area?

Many thanks in advance for all your help.

Is it likely to cause a problem?


Clay by it's nature is a damp material, it tends to stay damp even when built upon.

If the clay dried out it would shrink and then you would have major problems.

One of the biggest problems of houses built on clay are trees, in dry weather they suck out the moisture from the clay and cause the clay to shrink, causing the house to move and crack etc.

Having cut the concrete open how should I re-seal?

Just fill the concreted area with concrete, not sure about the red screed, but it could be some form of tanking?

My house is built on clay, and two of the ground floors were concrete. I got the floors screeded with asphalt, which stopped and damp from rising up.

_________________
DIY | Donnas dream house

Thanks for the reply, I'd seen a few ppl had viewed and at last a reply! What you have suggested makes good sense. How much did the asphalting cost per m?

Thanks again.

I can't remember the cost as it was about 11 years ago.

_________________
DIY | Donnas dream house