Can I pour a cement slab onto an existing slab?

Question

Can I pour cement onto an existing slab? Its a patio, so no heavy weight will be on the slab besides normal patio furnature and 2 fiberglass post that supports the roof. The patio is 12'X20'. I want to raise it 3 to 4 inches. The existing patio doesn't have a really smooth finish on top that I can tell.

Answer 1

What's on top isn't what will likely cause the problem, it's what's underneath the first slab, it all depends on whether the ground will support that much weight evenly. If it doesn't you will have more work to re-do if it cracks on you. Are you a dice roller or not, that's what it boils down to.

Answer 2

Since you're putting at least two inches above the existing slab, you can probably get away with it. The old slab won't count toward the load bearing since it won't be solid. Two inches should be enough for your load. You will also want to extend the patio about 4 inches so the new slab is a shell around the old one and not a covering on it. Driveways and such, bite the bullet break up the old slab and start over.

Answer 3

You will probably want to have pieces of rebar sticking up out of the old concrete, every 12-18 inches around the perimeter, so as to hold the new concrete. Also, you will want the finishers to cut lines in the new pour to help control the cracking. Three inches is a good additional amount.

Answer 4

yes , it came be floating or drill and doweled, make sure it flows away from the house, if possible use fiber reinforced concrete