Building over a drain/sewer

[Tgeorge]

Hi,

It looks like the semi-detached house I am purchasing has a drain running at the rear where I propose to build an extension. The property itself has no manholes or visible sewer but I can see that the two adjoining properties have manholes and I assume that a lateral foul drain runs between them in a straight line.

I have attached a diagram below showing the proposed property which I am extending to the rear and side (single floor). The red line shows the approximate position of the drain and manholes.

Given that my rear extension wall will go over the pipe, what options do I have? I have heard about "reinforced concrete floor slab", "cantilever" and "pad foundations and beams" but have no idea what there are and how much more than a standard foundation they would cost.

As I have not exchanged yet, I have no idea of the details of the drain - how big, how deep etc? Also is moving the drain a cheaper option if possible?

Is my extension a non-starter???

Any advice will be greatly appreciated..... especially as I am exchanging in two weeks

View media item 45232
Regards,
T George[/img]

 

[^woody^]

There is normally always a technical solution, but unless there are more details then no-one can advise further

 

[noseall]

Easy.

Move the chamber at the top of the image so the drain is outside the building. Then re-join the main run using new chambers.

It is likely your designer could use the new chambers in any case.

 

[Diyisfun]

My extension was similar, the pipe was bridged with concrete lentil.
BC was happy
or is it lintel

 

[indus]

Edited, as my post was not useful