Want to replace conservatory with extension but can't find my drain!

[Camulos]

Hi all. Thanks for your time.

We have a conservatory of around 5.45m x 2.5m at the back of our mid-terraced house. We are hoping to replace it with an extension stretching back a bit more (to 3.7m). However, the absence of a manhole/drain cover in our back garden, and the presence of them in my neighbours' patios (where our conservatory lies) makes me think it must be under the conservatory - though, as far as I can see, not accessible. The conservatory was here when we moved in.

If the drain is there, I understand it's going to be problematic to build the extension, and we'll need 'build-over agreements' etc. It seems that we'd have to pay Anglia Water quite a bit of money to get it diverted, and also pay our builders to do so.

Not sure what to do next really! Does anyone have any advice on how I can firstly confirm the drain is indeed under the conservatory - short of smashing up the floor and looking? Should the previous builder have tapped it off somewhere else? I can't find any other manholes in our garden. Is it going to be a nightmare trying to get it diverted? Any advice welcome!

Also, am I correct in thinking that being 3.7m from the house, we will require planning permission? Is this generally easy and straightforward?

Sorry for the many questions and thanks in advance! Not having a clue about this side of things is making my head spin!

 

[noseall]

The drain and any subsequent IC's may or may not be a problem depending on how the footprint of the proposed extension affects the drain.

Are you familiar with the sewer run that serves your properties, i.e. the position of the common line etc? Yours may run down-stream and into your neighbours IC, removing the need for a chamber on your property.

It may be just a case of a build over agreement with a proviso that you modernise (renew) all the drains beneath the footprint of your proposed extension. We have done it many times.

 

[garyo]

Have you pulled up the flooring to check that there's not a double sealed manhole cover in the conservatory floor?

 

[Ian H]

If your building over it then they will likely want a CCTV survey before and after if the shared drain runs under. The CCTV will show you if you have s buried manhole and also exactly where it is.

First thing would be to lift the neighbors manholes and see if it looks like there is a drain running parallel to the back of the houses.