Condensation

ccluedo

I had a similar problem 14 years ago with a 1970's house that had had absolutely no issues in the previous 12 years I had owned it.

I called in a firm of consulting engineers who said that the solum was 800mm below floor level whilst ground level was 450mm below floor level. No obvious explanation could be found for why this had only become a problem now.  Outer walls were all damp to varying degrees sub walls dry as a bone. Parts of the solum looked like the mashed up concrete u describe.

Long story short, adding a drainage system around house wasn't a viable option so I followed their other recommendation to upfill the void with a lightweight material (large slabs of I think it was 2400 x 600 polystyrene) which provided a platform for installing a DPM at ground level giving normal construction.  Altho there were airbricks all around the house, we added another one on each side.

It was extremely stressful, not inexpensive and we had to patch the floors in every room where they had taken large cut outs for ease of access.

Happy to say not a single issue in the last 14 years and recently had all the floors up again as could now afford to replace them all with P5 caberfloor and insulate at the same time.  Not a bit of damp or mould etc to be seen, so was well worth it.  I can say that in hindsight - at the time I was sick to my stomach!

Hope something in that might be of use to you @youth_leader

(I imagine that I would have to declare this if I ever put the house on the market but as it is 100% fixed I would hope it wouldn't affect mortgageabilty or price)

youth_leader

Thanks ccluedo, I've looked up what 'solum' means but still don't understand. Is it the 'base' that is dug out for the house foundations?

stuart45

The solum is the ground below the floor. Years ago the area was dug out with the foundations as it was easier take the lot out than dig trenches for the sleeper walls. 
Nowadays if a suspended timber floor is used there is a concrete oversite higher than ground level below the joists. 
In old houses with a 3 or 4ft void under the floor when the water table is higher than this water will enter the void.

ccluedo

youth_leader said:

Thanks ccluedo, I've looked up what 'solum' means but still don't understand. Is it the 'base' that is dug out for the house foundations?

As Stuart45 says, it's the ground beneath the floor i.e where u are saying "ground is like mashed up concrete"