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Groundwork for first time laying a patio

Postby Del26 » Wed Apr 28, 2021 1:14 pm

I’m laying a patio for the first time, and have read up on guidance about ground preparation and depths below the damp course etc.
I have lifted up the old large council style slabs and started digging down to give me a depth suitable for the sub base + cement + slab, as the previously slabs were only around 75-100mm below the dcp.
The problem is I have now dug down around 120-150mm below the dcp and found a hole which looks to be around 2 metre square filled with large stones, which I believe must have been created as a drain off point from the conservatory that the previous owners had built. It looks to be just a hole (depth possibly around 500mm with no drain off pipe.

The question is, what should I do?
1. Leave the hole with the stones, and continue to lay my sub base on top?
2. Remove all the stones, and fill the hole with soil, before laying the sub base?
3. ?????

I intend to move the conservatory guttering down pipe, and will lay the slabs with a minimum 1:60 fall.

Any advice would be really appreciated.

Thank you.
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Simply Build It

Postby stoneyboy » Fri Apr 30, 2021 8:59 pm

Hi del26
It looks like you have some way to reduce ground levels so you new patio is well clear of the DPC. Suggest you remove all large stones and see what level this leaves.
Regards S
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Postby Del26 » Sat May 01, 2021 8:09 am

Many thanks for the response.
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