Pouring concrete over concrete

Bigbobdallas

What I am Doing is I have a front porch that someday is going to become enclosed. You walk out the door and it drops down about 6inches and proceeds to the front of the porch. I want to raise the porch that is there now to make it flush with the one that comes out of the house. I was going to drive some rebar into the exsisting concrete stem and lay wire off the ground and then just pour it solid. Is this acceptable to do it this way or do I have to bust up the concrete that is there. What is the best way?

comp1911

You should also rough up the current concrete surface and use a boding agent.

concretemasonry

You may also have to come up with a new set of steps for the new elevation levels.

SecretSquirrel

How soon will that "someday" be here? The reason I ask is that the purpose of having the offset (step down) is to keep water out of the threshhold. If you do pour the new pad without getting that new enclosure anytime soon then you'll have to slope it away from the house. I know that's got nothing to do with your original question but I thought I'd mention it.

rwwood

There are a number of things to consider here. First off, will you be raising the level of the outside porch to make it essentially a walkout from the house, in other words will there be any step left at all? From your description, it sounds as if you will be bringing up the finished porch floor to a levell where you would have concrete above the sill plate and rim joist on the existing house. If you finish enclosing the porch in a short time, that might not be a problem, but other wise you are apt to have water get trapped between the new concrete floor and the wood framing, which will result in a rotted sill and rim joist. Even after the porch is enclosed, you have enclosed an area that is no longer open for termite inspection.

Secondly, how solid is the existing slab? If it is solid and level (not necessarily without cracks), you could probably pour the new floor over top of it, but I would put down a vapor barrier rather than worry about bonding to the existing concrete. You're talking about converting what was an outdoor space into an indoor space, and unless you want a damp floor, you should consider keeping moisture out a priority.

If the existing slab has sunk or is sloped or in any way not stable, then you willl probably have more problems by adding the weight of additional concrete on top of it.

Have you considered framing out the new floor rather than using concrete? If you're talking about 6" to 10", why couldn't you frame the floor?

My 2¢
rww

citybuilder

In our local language it is called 'NEERU' you have to apply this on one surface so that the two distinct surfaces have a proper bond!!