Help needed re: extending over straddling boundary drain!

[AB500]

Help! We need some serious advice! Basically, we have a terraced house that's around 6.5m wide. In the rear garden on the left hand side (looking from front to back) there's some sort of cover/hatch that diagonally straddles ours & our neighbours boundaries almost exactly half & half (currently has a wooden fence over it). See pic below:-

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• AB500
• 28 Aug 2014
• 1

Right now we have a PVC conservatory that sits next to it comfortably (visible in pic above), but we're thinking of replacing it with a proper full width brick extension. Between the hatch and edge of back door however, there's only about 8" / 21cm of space (enough for a single layer wall / conservatory but not for a double layer). See below diagram:-

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• AB500
• 28 Aug 2014
• 1

Our questions:-

1. Can that hatch thing be moved / built over as due to it straddling the boundary it can't be built inside with a double sealed cover over it? If so, what are the consequences / costs / who does it involve both the relocating work and the fact it's half under the neighbours side? Is it too much hassle?

2. Even if we don't build over it, but rather build up to the edge of it, given there's only 8" / 21cm of space, this doesn't seem to be enough to meet 10-12" / 25-30cm building regulations for a double wall. Likewise, from what I understand, the "strip footings" need to extend even more beyond the outer layer of a two-layered wall making the situation even worse? Would building into the existing back-door cavity work (not ideal though as it'll give us even less space plus make the room behind it darker)?

3. How common is it to have a straddling boundary hatch? What is it even for - sewer inspection hatch? We've lived here over 30 years (since it was built) and it's never been opened.

4. What other options are there? Anything we've overlooked / anyone with a similar problem in the past?

Any advice you can give is greatly appreciated!

 

[Hugh Jaleak]

It looks rather like an inspection chamber for the sewer, doesn't need to be lifted on a routine basis, but provides access to the sewer in the event of there ever being a problem.

Really need to check if it's a shared drain, i.e. serving 2 or more properties, and the size and depth of the pipework. If it is a shared sewer then it is the responsibility of the Water Company, (their sewer) and they have very strict rules about what (if anything) can be built on or near their pipes etc.

Moving it is not always possible, again depends on depth etc, you really need to ascertain the situation and likelihood of being able to work around it before going any further. A plastic conservatory is pretty lightweight, an 11" masonry wall is a lot heavier!

 

[AB500]

Thanks for your reply Hugh. I thought it would be more trouble than it's worth!

 

[theprinceofdarkness]

I had one like that on a Victorian house. It flooded once so I opened it up to discover a bit of 1" thick slate across the outlet, once this was removed it flowed again. Interestingly the line of the drain was angled towards my neighbour's side, under her lawn? My side drains headed towards her lawn as well. I reckon that there was a manhole some where under her lawn which was cut down and capped with slate which is now breaking up.
Its not only the drain inspection pit that needs attention in your case its potentially the line of the drains as well. You might have to bridge over the drains with footing on both sides of them to carry a proper wall. Or build your foundations(and wall) on your side of the drain if its actually on the centre line.
Frank