I have an 18 month old house with a walk out basement. The walk out is vinyl sided, Tyvexed, sheathed with OSB, insulated with fiberglass batts R-19, 2x6 studs with a plastic vapor barrier. The basement is unfinished and unheated, though the temperature this winter was always 55 or above and the humidity has been hovering at 45 to 55%.
Recently I noticed condensation between the vapor barrier and the insulation. I pulled down the barrier and the insulation to find that 60% of the stud bays were molding on the upper 1/3rd of the OSB and on some studs. The insulation installer said that they shouldn't have put on the vapor barrier until the house cured.
Is there any way to solve the mold problem (assuming I get the moisture under control) short of removing the molded OSB?
If I'm seeing mold on the interior, would it have affected the exterior of the OSB?
The insulation installer said that once the walls were dry, he could blow in insulation and if we drywalled it would solve the problem. Is this right or is the problem just hidden?
Thanks for any input.