After reading Rick's post and others about overheating and steam I have a question. How do you handle the vapor barrier between the rear of the Garn and the outside cold wall? The manual says combustible materials must be at least 2" from the chimney. If there is not a vapor barrier, wouldn't the fiberglass become saturated at the outside wall due to condensation? Wouldn't this would cause problems with rotting as well as R-Values?