I live in an older under insulated home that loose heat through the ceiling, corners and walls. Taking down the ceiling is not an option without major renovation. Presently I have two bats of 6" insulation, strapping, vapor barrier and the old fashioned 12"x12" tiles. In my kitchen and living room (an open concept)I want to attach rigid insulation to the ceiling (keeping the old ceiling in place) spray insulate the edges where it meets the walls, re-strap and install a wood ceiling. My problem is whether I will created an area of concern between the old vapor barrier and the new rigid insulation!