Extension built over private manhole-buying a house

Myf2001

I am buying a house that has a private sewer and had a drains survey this week.This has shown that there is a manhole serving 2 toilets that has had an extension built over it 18 years ago.They have a building regs certificate but no plans or other building works details. The surveyor said that if a toilet became blocked it would involve removing the toilet and using some specialised tool (bigger job and rodding from a manhole) Not sure whether this should totally put me off buying a dream house a) cost involved in an unlikely blockage scenario b) re-selling issue c) any other issues I haven’t thought of!

Any advice out there please

ritz55

My father brough a house back in 1993 with the same problem. For many years like about 25+ years he never had an issue. He did have an issue on one occasion and called out a professional company who managed to get a pipe down the outside drain and suck out lots of fat cost £500 at the time. The manhole is still under the extension and no further issues since.

sherlock228

building regs are not retrospective.
if it had sign off at the time, then it remains valid

I presume the manhole is now inaccessible due to a floor covering, meaning you cannot visually check if it is double sealed?
Dealing with a blockage is down to how easy would it be to lift the floor covering and access the manhole as normal?

Shedman

Not directly related to the drain issue but, if they've built over manholes due to an extension, have you checked whether the gas meter is now internal in case it was originally on what would have been the external wall but it's the wall they've built out from and, therefore, the gas supply pipe has been built over? If it is a plastic pipe then there is a risk that a meter reader or boiler service person might report that the meter needs to be moved outside (as plastic gas pipes inside are now deemed a risk).

We discovered this after living in our house for over 15 years as the previous owners had built out from the external wall where the gas and electric meters were but left them in situ so had built over a plastic gas pipe and we had to get the meter moved (otherwise they were going to shut off supply within 28 days of the notice). Luckily, as we were able to prove to our gas distribution network operator (SGN) that it was done before we moved in, they moved it for free (and did a really good job in difficult circumstances it has to be said) otherwise it was going to be around £2k or more

FreeBear

https://forums.moneysavingexpert.com/discussion/comment/82140682#Comment_82140682

I too have an extension built over a manhole. The work was done in the 1970s and has full BC sign off. Currently have vinyl tiling across the whole floor. Lifting it should the need ever arise is possible, but the biggest problem will be lifting the cover. Double sealed, and the lid is filled with concrete (read darned heavy). Last time I had to lift it, I needed to make some custom bolts and a lifting frame complete with jacking screws. This frame is stashed under one of the kitchen units for when it is needed again.

Albermarle

https://forums.moneysavingexpert.com/discussion/6683734/extension-built-over-private-manhole-buying-a-house

It was allowed to build extensions over manhole covers in the past, but not now.

I think until about 25 years ago, you could do this without any special permission. Then for about 10 years you needed a build over agreement with the water/sewage company, but after that (2011) you are just not allowed at all. Don't quote me on the exact details though !

We have one in our side extension, but it is only under carpet so could be accessed quite easily.