Uneven hardcore

[barrymac20]

Hi all.

Installing a patio. 400x400x40 tobermore concrete slabs on a sand base.

I am in the process of finishing the sub base layer, 100mm or so of 803 stone. I am having some trouble getting it level and i have run out of stone. I was aiming for 75mm from top of base layer to top of slab. 35mm for sand and 40 for slab. The hardcore is between 70mm and 90mm to the top of my finished level when measured in a few places. Is this an ok tolerance? It means my sand will be between 30mm and 50mm deep?

B

 

[Scarlet Pimpernel]

In my experience, you won't get hardcore that level and within the tolerances that you're looking for. That is why a sand layer or mortar layer is required.
Have you whacked the hardcore?

 

[barrymac20]

I have indeed. It was a bit uneven but not too bad. I levelled it a bit with sharp sand and whacked ot again before putting down my sand base layer. I'm laying slabs now so i hope to feck all the hard work pays off.

Thanks for your reply