Help advice needed re cold extension and damp

[mishel02]

I had a side extension built 3 years ago. The extension is freezing cold all of the time even when the heating is on. It also smells damp and of foist, the floor has started to sink in one corner and the skirting boards are loose. When my builder was digging the foundations they kept filling up with water, which he kept pumping out. I asked him about this and he said it was an old rainwater drain that ran down from my neighbors garden and into mine and ran into where the foundations were. The drain was broken and he said he would bury it in the concrete foundations and it would be fine and it would be sealed. However even after the foundations had been poured the hole still filled up with water. He told me that once the drain was empty it would stop filling up and not to worry.

My question is now that I seem to have a damp problem could the underneath of my extension be full of water? Was his information correct or did he tell me a pack of lies? I am very worried as there is a definite problem that seems to be getting worse. Thanks

 

[ree]

Suggest that you approach your neighbours, and discuss this with them.

Are the properties very old - because its not all that common for drainage to cross close to neighbours houses.

Then, if all agree, do tests down any likely drainage - peppermint used to be used - you would smell it above any cracked pipework.

Or, maybe, dig just outside the extension where the "subsidence" could be, and see if you can locate any drainage pipework.

Where is your nearest manhole?

 

[mishel02]

Hi thanks for your reply. The manhole cover is in my back garden and the drain in question that the builder buried in my foundations is not connected to my main drains. I have had my main sewage drains checked and they are fine.

This is a separate drain to carry rain water away from the houses I think.

The houses were built in the 1950s.

 

[ree]

If the mystery drain was intended to drain the rainwater from your neighbour's to a sump, it begs belief that it would have been allowed to cross and discharge on your land.

Have you confirmed that your rainwater is either going into, and through, your manhole or going to a sump on your property?
Its easy to check.

Thing is, its no good taking remedial action with the extension floor issues until you've sorted out the drainage business.

 

[tony1851]

If it is a ground-supported concrete slab sinking in one corner, it may be that the backfill was not properly compacted?

Skirting boards loose?

It seems unusual that a new extension which is heated should be so cold. Was proper insulation applied to the walls, floor and roof?

This has the feel of a cowboy job rather than a drainage issue.

 

[mishel02]

sorry to sound silly but what is a sump and how do I check if I have one? My rainwater from my gutters goes into my main drain in my back garden. This other drain is separate

The walls, floor and roof were all insulated and the building inspector signed everything off on the extension. We did have a problem builder who was useless and ended up doing a complete walk out.

Who would be the best person to ask to take a look at the problems as im not sure who to call and dont want to be ripped off again

 

[skhudy]

If the problem builder walked off did you have another complete the works?

Foundations filling with water, I'm not doubting what your problem builder said, but than can also happen if you have a high water table. My garden you hit water if you dig down 1m !

It's going to be difficult to work out the problem without inspecting e.g pulling up the floorboards (is it a soild floor or floorboards?) where it's "sinking" and checking the insulation, if your builder forsaw being kicked off the job I'm sure there are things they could do to cause future problems - how ever unprofessional.

I guess a building surveyor would check everything and determine the cause of the problems? You'd then have to get a builder to rectify, or perhaps a good recommended builder would be able to determine the faults.

The Damp, Pictures outside and inside, someone here might be able to give some ideas on reasons for water ingress.If DPC is in place and not being breeched, water shouldn't come up from beneath.