Home FAQs Overlaying & Whitetopping Concrete Can we pour cement over an existing slab?
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Can we pour cement over an existing slab?

Q: We want to pour a 30' x30' foot slab for a basketball court. We tore down a building that has a cement slab under it. Can we pour cement over this existing slab?


A:  First a clarification – what you want to pour is a concrete slab, not a cement slab. Cement is one of the ingredients in concrete, along with stone, sand and water. (Sorry – personal lifelong quest!)
Yes, you can pour new concrete over top of the old, but here are some things to keep in mind.
If your new slab will be larger than the old building, you need to be careful about cracks mirroring through around the perimeter of the old building. I would recommend using some extra rebar in these areas.
You should also prevent the new concrete from bonding to the old slab by using plastic or some other material between the two. If you don’t do this, all the cracks and/or joints in the old slab will reflect into the new one.