I just had a a question. Do I need a lot of gravel under concrete for my driveway. I live in California and get no extreme weather changes and I know this can matter in the long run. I have a guy putting concrete in our driveway, which is on a slope, used minimal gravel and rebar. Should this matter? Or should there be more gravel? Please help. Thank you
Do I need a lot of gravel under concrete?
Jul 31, 2020
4 Replies
The minimum is 4" for a common driveway, but for heavier vehicles or a "sloped" driveway, up to 12" may be necessary.
Depending on your sloped driveway, I would use a minimum of 6" and a max of 12".
Your written agreement with the contractor should specify the details of the job ? No written agreement or quote ? ... is he the cheapest guy ; talks real confident and friendly and brags about his great workmanship - can start tomorrow ; shows up in a beater pick-up with no business markings . ? Hope you didn't hire that guy.
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John T.
The most important thing is you need a stabilized base. That means you can't pour concrete over soil, you need something solid. If there is
16" of soil, then packed gravel and clay, then the 16" of soil needs to be taken out and backfilled with gravel or similar fill material and compacted. If you only have 6" of soil before you hit a sturdy, packed formation, then you only need 6". So how much you need depends on the local soil formation.
I'd like to see other driveways he put in, and I'd like to talk to those homeowners and see if he really put them in. (It's easy to gather a list of addresses with nice driveways.)
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