Buying a 4 Post Lift advice

Thanks for all the help guys! Lots of good insights here.

I have done a little research on the cement strength. Many lift manufacturers specify 3.5 to 4.25 inches thick with 2500-3000 psi crush strength. Trying to understand where these numbers come from seems to involve a lot of science with a lot of factors that are not easily understood.

If I have good concrete, then I am ok at 4 inches. However, as Rusty has said, if you have concrete that is substandard, not thick enough, or on top of a void in the base, that could spell trouble.

Has anyone done a check on their cement if they didn’t know the thickness for sure? Is it necessary?

The easiest thing I could think of would be to drill a small hole & see what depth I break through. Or maybe find someone who can test it with one of those fancy ultrasound testers.