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Is my drain under our conservatory? is this a problem for our extension?

Hi all. Thanks for your time.

We have a conservatory of around 5m x 3m at the back of our mid-terraced house. We are hoping to replace it with an extension stretching back a bit more (only another metre). 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!


2 Answers from MyBuilder Extension Builders

Best Answer

Hi there when planing any type of building work on your home or business/property it is always better to make inquiries in to planning regulation for even the smallest job now for your manhole cover not every garden has one depending on the age of your home you could try asking your neighbor if you could lift the lid of his cover mix food coloring in your toilet bowl and flush your toilet have someone stand by manhole and see if your drain flows through. regards Kevin


Answered 22nd Feb 2017

Hi Camulos,

Firstly I would recommend that you speak with a company competent in the surveying of drainage systems. They will usually be able to request details of drainage plans if they exist otherwise they can do a gps camera inspection/survey to ascertain and "draw" a nearly accurate plan of your drainage system. This may yield you with an answer as well as visual evidence of what is going on underground.
Surveys like this can be somewhat costly but if conducted correctly prove invaluable in such a process. A company that we currently use quite frequently will on average charge us between £600-£1,000 for a basic survey dealing with only a few connections.

It is worth checking through your local council planning record to ascertain what permissions were granted previously as well as checking to see if previous built over agreements were requested or purchased.

In terms of access in the event that a manhole is located under the conservatory, it may be worth considering a suspended concrete floor with internal access hatch which should help you avoid having to deal with a build over agreement and re-routing (do note however that your overall construction costs will generally rise if you go down this road).

In terms of planning permission requirements - it is best to seek advise or look through the provided guidance available on the governments planning portal as the ins and outs of permitted development is slightly more complex than a straightforward answer.
In general because your extension is under 4 meters you would require consent but not full permission, however there can be additional complications such as the shape of the existing house and whether the proposed extension is seen as a rear extension or a side projecting extension (if your house has a slight L shape at the rear then we have experienced instances where difficult councils will insist that it is a side extension and not a rear which changes what you can and cant do.)

Hopefully I haven't complicated this more.


Answered 22nd Feb 2017

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