I pulled up the carpet in the weird room/enclosed deck that is going to get an extra layer of drywall on the shared wall, & found out the shit that's underneath. First of all, I won't be able to lay peel & stick LVT right on the layer below because there are huge gaps. Plus one corner looks suspiciously dark, like mold. So after the drywall is done, I'm going to have to figure out what to do underlayment-wise. Another (thin) layer of plywood? Try to put in a layer of gypcrete?