mbc MBC insulated raft foundation. What did you back fill the trench around the insulated slab with?

[Omgiamgoingtobuildahouse]

HI. We have an MBC insulated raft foundation. We are on heavy clay and the house is on a slight slope. We need to landscape when the weather is better but we need to back fill the trench around the house. What did everyone else use? Architect is saying shingle! but this isn't stable. 'Normal' houses wouldn't have this and they would be surrounded by the earth that surrounds the foundation so do we put that back in? Its quite claggy and lumpy though. We were thinking type 1 with some French drains. Any advice welcome. W did out own groundworks so I have no one to ask. Thanks for any help.

 

 

[joe90]

Mine was not slab but we are on solid yellow clay, we backfilled our foundations with 50mm drainage stone as a French drain and a pipe to a local drainage ditch and it works very well.

[Dan F]

Think we used shingle around and over a land drain that was installed at the base of EPS, then just backfilled with spoils from formation dig.  If the shingle stability an issue if it's 400mm down?

[markharro]

Not quite the same issue @Omgiamgoingtobuildahouse and @Dan F but we too have a MBC slab and I am trying to work out how to clad the EPS base. At the moment I am thinking cement board stuck on using this stuff - https://www.dupont.co.uk/products/insta-stik-multipurpose.html Not sure how to "grout" the gaps between boards though?

[Dan F]

6 hours ago, markharro said:

Not quite the same issue @Omgiamgoingtobuildahouse and @Dan F but we too have a MBC slab and I am trying to work out how to clad the EPS base. At the moment I am thinking cement board stuck on using this stuff - https://www.dupont.co.uk/products/insta-stik-multipurpose.html Not sure how to "grout" the gaps between boards though?

 

Our architect proposed that we continue the render board into the ground, but the rendering company (Dryvit) recommended against this and wouldn't guarantee it.  So we had two option:

1) Have a break in the render board, with a drip bead and then another board going into the ground (rendered with a more waterproof product).

2) Stop the ender system at roughly FFL and then clad the EPS below this in something.

 

We went for option 2, and after considering trying to paint it, uPVC, as well as brick slips, we finally used GRP fake bricks from https://www.grpbuildingproducts.co.uk/.  They look exactly like engineering bricks, but much easier to install than brick slips.