Moldy Ceiling Fix

Q: How can I reconstruct the mold-prone ceiling in my uninsulated garage? I recently discovered moisture between the ceiling drywall and vapour barrier, and this has caused mold growth over the entire ceiling. I’m planning to strip the ceiling, then add insulation, vapour barrier and new drywall. Will this work?

A: It sounds like you've got your work cut out for you! Stripping your old garage ceiling and replacing it might be a good idea, but only if you identify and eliminate the source of moisture. It's almost certainly coming from condensation. If you don't need insulation in the garage, you might consider leaving it bare and open. But if the looks of this approach bothers you, then here's a plan: Apply 1-inch thick rigid sheets of extruded polystyrene foam to the underside of the ceiling joists, then put some fiberglass on top, between the joists. Seal all joints in the foam with expanding polyurethane foam as you put the sheets up (as added insurance against condensation), then apply a well-sealed vapour barrier below the foam and new drywall. As an added precaution, install some vents in the garage roof if they're not already there.