Foul drain - which way to route it

[Tim Streater]

We have a foul drain that is routed past the existing conservatory, about a foot out, I would say. The conservatory is due to be replaced by a rather larger one, so we (and the architect) were looking to route it off at an angle and then back again so that it would not be under the new conservatory at any point. The builder we expect to use wonders why, his view is it would be perfectly OK to use the existing line and just bridge the new foundations over it.

If we did that I'd expect to use a single 5 or 6 metre length of plastic to replace the existing ceramic. That way any joints would be reachable without digging the floor up in the new conservatory.

Anything I should look out for if we go that route? The architect thought it should be OK, but, like us, likes to avoid doing that is possible.

[Tim Watts]

I have a soil pipe under ours - with bridging and foundations going below the level of the pipe near the pipe, as per building regs.

It is a single 6m pipe with a manhole at each end just outside teh conservatory walls. Providing the pipe is covered in ample 10mm shingle all around and the bridging gives a good gap (again full of shingle) around the pipe, there is not a lot that can go wrong.

The structure is light and any minor movement easily absorbed by the gravel.

Read the building regs approved docs concerning drain pipes penetrating foundations. I have find links if you get stuck.

I would not use a suboptimal route *just* to avoid going under the floor. Lots of houses have soil pipes under half the floor - it's not uncommon. If you lose fall to take a tortuous route, you are more likely to have problems with blocakges IMO.

[Peter Johnson]

My extension had the sewer left in situ, and was bridged through the foundations using pre-cast lintels, all approved by the building inspector.

[Roger Mills]

Who's foul drain is it? Is it a private one which serves *only* your property, or is it shared by any of your neighbours? If the latter, it will now have been adopted (as of 2011 I think) by your water company - and you'll have to get *their* permission to build over it. They may insist that you pay for before and after CCTV scans to show that no damage has occurred. Either way, you'll need to bridge it with a lintel supported by concrete which goes down below the level of the pipe. If it's currently a straight run, I wouldn't divert it because that would introduce angled joints - which are more likely to block, and will need rodding access.