laying new drains, what to fill the trench with.

[browfish]

I am laying new drains around my extension to serve my new bathroom and kitchen. I have read the code of practice for drainage but am not sure of a few things. I am using 110mm plastic but does this count as ridgid pipe or flexible. I am basically trying to work out what i should be laying the pipe on. should this be 100mm of pea shingle?
what should i backfill with? can this be the soil excavated?

The excavation only takes me down to just below the top of the new foundations so there is no risk of disrupting these.

Also, where the pipe penetrates the cavity wall beneath the lintels already installed, a ridgid material should be used and filled with a compressible sealant. What sort of material should be used? obviously wood would rot, metal would rust etc and what sealan?

thanks

 

[steve1978]

Yep lay your plastic drains on 100mm of pea gravel then cover them with same then use the soil you dug out to backfill but remove and big rocks of bricks first.

Think what they are trying to tell you is not to use plastic pipe through walls as its normal practice to use clay pipes through walls etc and the compressable material we normally use is rockwool or simular product.

 

[browfish]

Should the compressible material not be something that vermin wont eat through/remove? Surely rock wall can just be pulled out?

 

[steve1978]

Nothing to stop you rendering either side if you like. if your thinking along along those lines don't use plastic pipework. also whilst we are thinking rats make sure you use a black multiquick when connecting your toilet as rats will bite through any other colour as light shines through the others.