drains through foundations

[Martin Carroll]

I am up to DPC level with my foundation and need to get the foul drains in place before filling with hardcore for the slab.

I have left gaps in two places for the pipe to go through the wall and have a few questions.

Part H tells me that I have to "mask opening both sides with rigid sheet material" and "fill void with compressible sealant". It doesn't state material for these so I was guessing plywood for the sheet material, not sure about the compressible sealant though?

Also what would be the appropriate distance to set the vertical pipe running through the slab away from the wall? One is for an internal SVP from an upstairs toilet (will be boxed in), the other is for a toilet in a downstairs cloaks?

Cheers

Martin

[sm_jamieson]

I would use a compressed cement board for the sheet material - you know the type that replaces that old asbestos/cement boards used for garage roofs etc. Simon.

[The Natural Philosopher]

Expanding foam.

That must be a new reg. I just shingled round mine..

Whatever you like.

[Phil L]

If you seal each side, how are you menat to insert 'sealant'? - FWIW, we've never done anything with them and no BCO has ever shown the slightest interest, except to see that they have suitable lintels across the top and that no weight from the building will be resting on the pipework. We've just filled inside and out with MOT and no one's cared...although they do want the slab to be reinforced with steel, and he amy even want the drains to be completely encased in concrete underneath the slab, but this is usually down to individual BCO's

The SVP is existing so that will have to line up with the upper part of the pipe (use a plumb line), the new installation is different - close coupled ones are a PITA, but the conventional flushpipe ones are a doddle because you can adjust the length of the pipe....I'd leave the drain 100mm from the wall

[Hugo Nebula]

On Tue, 19 Feb 2008 23:08:37 GMT, a particular chimpanzee, "Phil L" randomly hit the keyboard and produced:

Sometimes when a pipe has to pass through concrete, I'll ask for a 'void former' of polystyrene or mineral batts wrapped around the pipe. Otherwise, just pea gravel or scalpings around the pipe. MOT isn't really a good idea, as it isn't very flexible.

Where the slab is less than 300mm above the top of the pipe it should be protected by casting the pipe in with the concrete of the slab. How one manages to get a DPM and insulation around the underside of the pipe and concrete surround has never been satisfactorily explained, therefore the easiest option is to reinforce the slab over about 300mm either side of the pipe.