We just recently took the grout off of our shower and found we had a water and mold problem. We have removed some of the tiles and are waiting on call backs from local contractors. The insulation is wet and torn and looks like mold may be growing on it. The studs are wet and may have mold as well but are still solid. The shower is on an outside wall but there was never a plastic barrier in place. We want to fix this problem and ensure no more mold grows. What things should a contractor do to make sure the problem doesn't repeat itself? We are considering replacing the shower with a fiberglass shower since they are unlikely to have grout fall off and cause the problems we've encountered. Are there different grades of fiberglass or other non-porous surfaces we can use for a shower? We live in PA.