Depth limit on hardcore Drainage pipes, concrete, footings and foundations. Post your questions and find answers here

[Grumpy Boy]

Hi,

I have just bought a barn to convert (so expect a lot of requests for advice!), and I havee to build the double-garage first in order to comply with planning regs & bats.

The general yard area (surrounding the barns) is about 1m higher than the field where the garage is to be located. I understand I need to use hardcore as a base under the slab/footings etc, but I was not sure if there was a recommend maximum height of the hardcore & how it should be retatined.

I think that I need to dig a retaining wall (again using hardcore & concrete as a base/footing), which will hole the hardcore in place. I can then lay the slab DPC etc as normal.

Thanks.

[stoneyboy]

Grumpy Boy,
You will need to build the outer walls of the garage first thereby forming an enclosure for the hardcore. The depth of hardcore needed (and the foundation depth) will depend ground conditions - the softer the ground the deeper the depth of hardcore needed.
end

[Grumpy Boy]

Thanks Stoneyboy.

The ground is preety good, so the usual depth of hardcore & footings for wall etc.

I was just concerned about the "above ground" hardcore depth - going to be about 1m before the slab/dpc is laid for the garage base.

Will the retaining wall be suitable for this. I guess so but wanted to check.

Thanks again.

[elwood]

Hi

There's a maxium stone fill depth to a ground bearing traditional slab
I think its .600mm but not to sure (One of the other guys might know)
after that you will have to suspend the floor.

Bye

[stoneyboy]

Grumpy Boy,
If your garage floor is going to be 1m out of the ground take elwood's advice and form a block and beam floor. The alternative would be to construct 225mm walls and fill with carefully compacted hardcore.
end