What Type Gravel For Wet Location

72chevy4x4

I'm going to put a slab in a wet location-drainage from high side to low side of pad will be achieved with drain tiles, but the location is wet. Did I mention, its a wet location?

what is the best gravel to use in this circumstance? I'm guessing pea gravel would give best isolation from moisture in soil-is a 5/7 ok? what about crush and run-it would really lock together and give a good strong base, but I'm afraid of moisture problems seeping up in the future. The top of the slab isn't going to be much higher then the surriounding area-I'm picking up the pieces and completing a pole building, so the building is erected, not finished-therefore the walls are in place. Should the final product be treated (pole barn)?

Chris Johnson

What is the existing ground? how far down is it saturated? This will help determine what is the best base to put in and how far you need to excavate down, what ever you use for the base, it needs solid compaction, like use a small ride on roller is possible, cover with 10 mil visqueen a few inches of sand, build a rebar cage than pour minimum 3000 psi floor.

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Chris

dirt diggler

use #57 stone


(assuming it's called that in your area) - but the 3/4 gravel

72chevy4x4

are you recommending the visqueen on top of the gravel and two inches of sand on top? Can you describe the function of the sand please? What would happen if water would get atop the visqueen layer under the concrete? I'm not familiar w/ the product-would it trap the water (unless there was a perfect crown to the base)?

Chris Johnson

The visqueen helps with hydrostatic pressure, you indicated a wet location, if the water is coming up from the ground and you can't control it this will help prevent it from pushing on your slab and forcing it's way through the inevitable cracks, sand will allow the water a easier path of travel should water get between the bottom of the slab and the visqueen. crowning the base would be great if you can. Visqueen is a thick poly membrane, similar to Poly Vapour Barrier, we buy it as 10 mil thickness usually comes blue or black in colour. Fast Form makes footing products, I have seen some fairly wide rolls and this too may do the trick for you.

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Chris