Hey people, I’m trying to make a basement floor nice and level. The problem is the floor was poured over bentonite, and it has heaved over the past 24 years. I haven’t seen any signs of moisture, but threre’s alkaline and flaking where the concrete cracked. I would like to make wedges out of treated 2×4’s for the low spots and then a sheet of visqueen and finaly plywood. Will this work and will there ever be a chance of molding under the plywood? Thanks for anything you can offer. J.
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In the Denver area bentonite is aproblem and local code requires basement floors to be built on top of a steel framework suspended above the dirt below.
I live in Westminster, and I think some codes were overlooked in my neighborhood. I was just looking for a way to fix the problem without tearing out all th concrete and redoing it. J.
Depending where you are around there , there is a layer of really hard dirt, (Think its called calechi (sp) or some such thing.) its so hard you can hardly dig it with a shovel.Its real fine and real hard. It makes a temporary water table above it when it rains for a week or so and will cause all sorts of drainage problems.Your floor may be on top of that and not bentonite..Lived in Arvada and Westminster was across the street..
Bud
If the concrete is heaving, anything you construct on top of it will heave also. With a sleeper system attached to the concrete you would put the plastic under the sleepers, directly on the concrete. Sounds like you might want to talk to local contractors about how they deal with those clay conditions.
Bentonite expands when it gets wet. Thats what makes it so good for sealing ponds and stuff. I would suspect the ground moisture is your problem.