I need some advice please. I am redoing the floors in my parent's house. I need the floors as level as possible because we are going to install LVP flooring. The living room had carpet, but the kitchen had tile. The kitchen has a 3/4” subfloor and a 5/8” layer of underlayment and a 1/8” layer of underlayment on top of it. After tearing out the tile, and there is a 5/8” difference from the kitchen floor to the living room floor. My question is. Can I install another layer of 5/8” plywood underlayment on top of the other layers to make the kitchen floor even with the living room floor, and if I do, is there any special way I should install it? Do I need to screw directly into the joist or the subfloor?
2nd Question is. When tearing up the tile, a small section of the 1/8’” underlayment ripped up. Do I need to patch it if I install a new layer of plywood on top of it, and if I need to prepare the 1/8” underlayment, what’s the best way to go about repairing that small section?
Any advice would be greatly appreciated. I've attached photos showing the damaged 1/8" underlayment and the 5/8" height difference in the floors.