Foul drain - which way to route it

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.

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

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.