Single storey extension - Planning App. and Building Regs.

I want to put up a single-storey extension with flat roof across the back of my house (semi-detached). Neighbour's foul water drain runs right underneath where my extension will go (e.g. from my neighbour's garden, over our boundary, under my garden and into communal sewer the other side of my proposed extension).

Will it be okay to build, or do I need to get drainage survey done / apply for drainage easement? What happens legal-wise if the drain blocks / collapses in the future?

Also, do you know what is the maximum distance I can build out away from my house? 3m, 3.5m, 4m are figures I've heard mentioned. Obviously there may be a loss of daylight issue - can the neighbour legitamately object, and what would they need to prove?

Any advice appreciated!

It depends if the drain is a public or private sewer, on whether you need surveys etc (ie if its a public sewer you do)

Search for " permitted development " rights and you will get the volume allowance. Work under PD can not be objected to and does not have to take into account daylighting issues.

Its a m3 allowance so dimensions out from the house are not relevent

Im also building a single storey extention to the rear of my property and have a similar problem to yourself with regards to the drain.

although i am not actually going over the drain i am very very close to it and have had to enter into a 'build over agreement' with anglian water, at a cost of £262.

I was also told by the BCO that if i was to build over the sewer pipe suitable lintels would have to be in place to protect the pipe and if anything happens to the pipe in the future the water authority have the right to dig up your extention.

Sorry if that sounds a bit scary but im finding all this out now as i go along with my extention, just seems to be one thing afta another

Hi,
I am currently doing the same thing and had the same drain problem. I called the local water authority and asked ifthey had any interest in any drainage on my property and they said not. The sewer is in the end of a run of houses and is 2.5 m deep. I needed to have piled foundations so as not to disturb it.
It will be inside the new extension and should be accessible in the event of problems but I think I'm going to put it under the new floor with the understanding I can get to it if I need to.

Hope this helps. I'm having my own problems regarding extras ! see other posts.
Good luck

Timmo