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Groundwork & Foundations

Pad foundation - depth query

Hi there,

I've got some SHS posts going into my build (extension, so the SHS are being used with UBs for an opening) and had a query with the pad foundations.

Our engineer advised to try to get 1m2 around the SHS base, however as it's going in the existing property, how far down do we pour? Do I have to dig down to the existing slab (so removing screed/insulation if it was above the slab) and then pour from there up or do I need to go further?

Thanks!

1 Answer from a MyBuilder Groundworker

Best Answer

You need to excavate below the existing slab and into the ground until you reach good firm compact condition. Loading an existing slab will potentially make it unstable and possibly fracture. The engineer is correct, 1m2 of excavation will also spread the load on to the excavated ground.

2017-09-20T18:40:01+01:00

Answered 20th Sep 2017

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