Building over a stream

Postby sd75 » Sun Aug 14, 2011 2:49 pm

Hi everyone
We are looking into taking down a conservatory and replacing with an extension but our property has a stream cutting across the back garden and underneath part of the bungalow. This continues under our road and beyond. I doubt we would be allowed to close it up / block off our section of the stream. Can anyone advise us as to how difficult / additional cost this would incur with laying foundations ? The road has no history of flooding and there are no visible signs of subsidence, leaks, cracks, damp etc.
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Simply Build It

Postby xavi99 » Mon Aug 15, 2011 9:28 pm


Foundations need to be excavated down to suitable firm ground. The joy of excavations is that you never know when you will reach good ground until you do the work unless you have dug a few trial holes.

It all depends on how deep. If you are into silty river bed then you may need piles but if you are either side of the stream then a traditional foundation with beams bridging over may well be good enough.

I would suggest consulting a structural engineer at an early stage. It is a difficult one to assess on the basis of a post but at least you are aware of the issue.

Good luck,

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Postby welsh brickie » Wed Aug 17, 2011 3:24 pm

you need to lay a large diameter pipe,to allow the water through and under the consevatory,excavate your foundations as normal but where the foundations meet the pipe encase the pipe in concrete.Also at the start of the pipe you need to create a concrete wall around and under the pipe to divert all the water into it.
Remember this is just a guide all this will have to be passed by the building inspector
welsh brickie
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Postby sd75 » Thu Aug 18, 2011 8:08 pm

Thankyou both, appreciate it
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Joined: Sun Aug 14, 2011 2:29 pm

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