How many inches of subgrade and subbase below 4in backyard concrete?
by
Liz M
My contractor put 7 inches of subgrade and wants to put 3 inches of subbase from road base below the 4 inch concrete pad in my backyard. It is a big area of concrete around two connected side of the house. So it would be L shape with more than 35 inches on each side. I was wondering if the subgrade (DG, I was told it is some kind of mountain shaved and crushed to sand with mini stones) should be thinner, like 5 or 6 inches, and have the road base subbase thicker to at least 4 inches. Or have one inch of DG on top of the 4 inch subbase. What is the best foundation combination for the concrete in the backyard?
I told my contractor the stone yard recommend put the sand on top of the roadbase to make it flat. My contractor told me sand would stick to the shoes when walking inside the concrete on the day work is done, and when lifting the feet while walking inside the concrete, the sand may get into the surface of the concrete. Thanks for your advice.
I told my contractor the stone yard recommend put the sand on top of the roadbase to make it flat. My contractor told me sand would stick to the shoes when walking inside the concrete on the day work is done, and when lifting the feet while walking inside the concrete, the sand may get into the surface of the concrete. Thanks for your advice.
2 answers
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It sounds like he may have practical experience the stone yard wouldn't actually have. If he is qualified, and follow your local codes and regulations, perhaps he knows what he is talking about If you want a second opinion, you should ask someone in the same profession, not necessarily a competitor.
Adrianne C
on Jun 22, 2014
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Thank you for sharing your thoughts.
Liz M
on Jun 22, 2014
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