Bricks, Masonry, Asphalt and Concrete - Raising existing garage slab

What are the important things to do when pouring concrete on top of the existing garage slab to raise it 3.5" to the level of the house? This room is going to become a new bedroom. The rest of the house is on slab and we are in the deep south. We are almost certain the existing slab has a vapor barrier under it.

One of major things I am concerned about is the wall meeting the new slab. OSB is the current interior wall material and I plan to leave it and drywall over it.

Hi,

There is not real problem in pour concrete over concrete, but there are some important points:

- The new concrete will never "glue" with the old concrete or with the walls. So, you'll need to wire them with steel. If this conection is not OK, both layers and the walls will work as separate pieces, and the new one will surely crack.

-Be sure that the garage floor is 100% clean before start (oil spots are the worst)

- You need to be sure that with the new floor thickness the garage door (and other doors) will open OK.

- Check drainages if necessary

Hope this helps!