Adding Rigid Foam To Existing Interior Walls. There is no scientific or technical justification for John Clarks statement that you could trap moisture within the drywall and generate mold. Immediately I felt a huge difference.
Plywood over the foam and cap it with 12-in. One of the best ways to improve wall insulation is to put in spray foam and it is not impossible to add spray foam to existing walls without tearing up the walls. His goal is to boost the R-value and improve the air-sealing in exterior walls by adding a layer of rigid foam insulation on the inside after filling the walls with cellulose.
Insulate the walls of an existing home by removing the existing cladding and installing rigid foam insulating sheathing to upgrade the major building enclosure.
RetroFoam of Michigan has installed spray foam insulation in. Polyicynene and polyurethane are. How It Works. Remove existing wall cladding and trim.