Building near to manhole/drains

[diyer1519]

I'm planning to build a garage in my garden. I'm going to use bricks/blocks to build it so it will be a fairly substantial structure. Unfortunately I will need to build over a manhole. It's quite deep (I haven't measured it but it's definitely more than 3m) and one wall will need to be built within a metre of it. The wall will also be built over one of the pipes, which is also more than 3m deep.

I'm happy to have the manhole cover in the garage - it's not ideal but I can't see any way round it.

My big problem is with the foundations. I've had a look at the building regs and they seem to say that I will need to dig to the same depth as the manhole for my footings (this is not really practical). Before I pay for a structural engineer I would really appreciate any advice about what I'm likely to have to do for the foundations, then I can decide whether to go ahead with the project or not.

Many thanks for any advice

 

[spada01]

I'm planning to build a garage in my garden. I'm going to use bricks/blocks to build it so it will be a fairly substantial structure. Unfortunately I will need to build over a manhole. It's quite deep (I haven't measured it but it's definitely more than 3m) and one wall will need to be built within a metre of it. The wall will also be built over one of the pipes, which is also more than 3m deep.

I'm happy to have the manhole cover in the garage - it's not ideal but I can't see any way round it.

My big problem is with the foundations. I've had a look at the building regs and they seem to say that I will need to dig to the same depth as the manhole for my footings (this is not really practical). Before I pay for a structural engineer I would really appreciate any advice about what I'm likely to have to do for the foundations, then I can decide whether to go ahead with the project or not.

Many thanks for any advice

Only large garages need BC - over 30m2. Are you sure yours needs it?

I've built over drains before and used a lintel to take teh weight of the blocks and when at foundation depth with teh drain, boxed it in with ply then lintelled over again. I wouldn't want to sit foundations on top of where a drain was underneath without protecting the drain!

 

[RedHerring2]

I'm pretty certain that your foorings will need to go below the invert level of your drains. Not by a long way, maybe just 50mm or so.
It may only be needed in that area. The rest might be just normal depth, but it sounds like you'll need BC approval for that.

Another similar post:
//www.diynot.com/forums/viewtopic.php?p=1977329

There'll be more in the "Similar Topics" at the foot of this page

 

[noseall]

3m deep! Horrific!!

Not only will you need to go as deep with traditional strip footings, but you will have the added headache of trench collapse due to disturbed ground.

Piling