Help moving drain and Inspection cover

20 Dec 2007
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United Kingdom
Planning a conservatory, but directly beneath the whole length of the footings for one side dwarf wall, is the foul water drain going all the way down to the bottom of the garden, with an inspection cover just where the dwarf wall will meet the existing house wall.

Can anyone give me any guidance on what I can and cannot do here, I'm guessing that I can't have the drain enbedded in the footings, but if I move it in, it will be under the concrete conservatory floor, can't move it the other way as it's right up to next door's fence. Also I don't really want an inspection cover in my conservatory floor either, but If I move this down to past the end of the conservatory, it would be under 4' of soil, because the garden steps up where the conservatory will end.

Any help much appreciated.

Thanks, Jon
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you are allowed to build over a drain so long as the pipe passes through the foundation at 90 degrees or even slightly diagonally.

you are not allowed to build directly over a drain 'in-line' unless the structure is supported in such a way that no weight will be on the drain.

inspection chambers can be relocated up or down the line depending upon feasibility, and the complexity of re-routing the drains entering the chamber.
Even if you complied with the regs. building the cons. wall foundation directly over & following the drain run is a really bad idea for obvious reasons; apart from the additional expense involved, you would probably have to knock the cons down in the event of a problem! As noseall says, a foul drain can run underneath the cons as long as you have lintels over the top of the pipe to support the wall & reinforce the slab where it runs over the pipe route or you have reinforcing mesh in the whole slab (which I have). My cons. is, in fact, built directly over & at 90 degrees to our foul drain run with an inspection cover either side. It’s not the ideal situation but it’s a lot less hassle than moving the drain; unless it of course it collapses but there is no reason why it should if it’s properly protected!

You can also have the inspection cover inside the cons. if it’s really a problem. This sounds horrendous but you can get special air tight covers & an over-frame that will take the tiles/flooring; it obviously wont be invisible but can get you out of a hole when needs must! I was going to do this but, in the end, made the cons. slightly smaller instead. You could move the inspection cover but you need to check the regs. 4ft is probably OK but I believe there may be a maximum depth you can go to.
I think the options are clear - move the drain or move the wall, and move the manhole or fit a sealed cover and have it inside

Internal covers are not that bad and when the flooring is laid in the lid, only the thin metal perimeter edge is visible
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Thanks very much for the info folks.

Just one more thing. since I know sweet nothing about inspection covers. If I have it past the cons, 4ft down under the lawn, is there a sort of extension I use to bring the cover up to ground level.
I don't recall the actual dimension, but deeper than 1m would probably require step irons, so a preformed plastic riser may not be any good

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