Thanks all. The existing slab is on grade (sandy soil) and the finish will be tile. Good observation on the details. I intended to specify removal of drywall and form with 5/8" plywood (studs are at 16" o.c.) and the electrical outlets raised to NEC code height.
I have a home owner that would like to raise his living room which is 11" lower than the rest of the main living area of the house. This would require pouring 11" of concrete on top of the existing 4" monolithic slab. I would generally be concerned about shear along the perimeter of the overlay...
