Water in foundations.....

Mike - this very much depends on the type of soil and for how long the water was running. The water could soften clay or wash away sand, or in gravel or chalk it might have very little effect. But even if you know the soil type, nobody can say for certain what effect the water may have had - the only way to find out is to dig a trial hole to expose the soil at the bottom of the foundation. But is it really worth doing this? My feeling is that if the water had caused any foundation problems they would probably have shown up by now.

So my advice is only get in a Building Surveyor or Structural Engineer if you see any cracking to walls or ceilings, wrinkly wallpaper or jamming doors/windows.

Peter

Hi Mike. This is a classic cause of subsidence for houses built on clay soil. However I dont see what you can do about it after the event, other than cross your fingers. If there is no structural house damage, I dont see a need to engage a surveyor. If all is well, it probably will stay that way.

Regards, NT

Is it? No. It isn't. My old house when demolished had a lake under it, on clay soil..

The biggest danger is shrinkage when it dries out, not any damage from getting or staying wet.

Soil is wet. Foundations are designed - or rather have developed over years - to cope with it.

All the leak has done is raised the local water table a bit. Now its gne back down to where it was.

If you didn't get heave (soil expansion to crack foundtaions) when it was wet, its unlikely you will get subsidence (soil shrinkage due to being dry). In this respect raised floors (which it sounds like you have, although I can't actually envisage a garage with a raised WOODEN floor...) are an advantage. There is an air gap to ansorb expansion without actually lifting the floor!

The right advice is as abocve. Do nothing. If any signs of cracking show, then yes, you may need to underpin locally on the advice ofd a structural engineeer, but I would say you have 95% chance or better that nothing needs to be done now, or ever.

Cheers All,

We had a surveyer out yesterday, the insurance company wanted to send one, and he said that all was clear!

Thanks again.

Mike

What sort of quantities were you talking about when you said "a leak"? If it was a continual small quantity it would have made no difference overall.

Look at how much rain falls in an heavy shower. And trees pour it back up by the ton every day -and the ground is at ease with all that.

Clay is unlike other types of soil in that it creeps under weight when it gets wet. Ask any surveyor.

Presumably your house was built with foundations sufficient for the wet conditions. Most arent.

Regards, NT

I'm fairly sure it was quite a small leak, didn't actually find the leak (got near it) as ST relaid the service pipe instead.

It wasn't. It had at best 8" deep brick plinth laid on the clay :-)

The chimney area was totally un injectable, and soaked up water like a sponge, as did the spine wall attached to it.

The whole house was too rotten to be worth renovating, so we pulled it down and built a new one. #

HOWEVER even those completely ridiculous foundations were, in fact, adequate for an old timber framed house. Might have had problems tho if we had attempted to soldve the damp problem by e.g. digging a french drain around the house and lowering the water table. My giess is that part of the house would have sunk a couple of inches.

New house has up to 2.8m deep concrete foundations :-)