Mold/ventilation problems in an old passive solar house
I just tried to post a long comment on the vapor retarder/barrier article and was blocked for spam so I'm trying again here. I'm under contract for purchasing a 1979 passive solar house in Southern Maine (near Sebago Lake, but at higher elevation). The house needs a lot of work, which we were expecting, but on top of all that they unfortunately found moderate to high mold growth on the roof sheathing and rafters, along with improper insulation/ventilation practices. The house has a cathedral ceiling spanning the south side of the house with a very steeply sloping roof on the front (used to hold solar panels). There is a second floor spanning the north side of the house. Then there is a small attic space on the south side of the house that is partly finished with an unfinished crawlspace behind it. The mold is in the crawlspace and above the finished attic space.
There is a standing seam metal roof (2008); roof construction is 2 x 12 rafters with 11 inches of fiberglass (R38). To block air infiltration, a 6-mil vapor barrier surrounds all exterior walls and the roof. (That info is from an old article written about the house.) The house used to have an attached greenhouse that was replaced (2008?) with a hot tub (which vents into garage, ugh). I don't remember seeing any ceiling fans at all in either bathroom. And there are can lights in the attic space above the kitchen that of course weren't insulated.
We have a mold remediation quote for soda blasting, etc., but they won't do anything to reinsulate, fix ventilation, or replace ceilings. We got a quote from a weatherization company and I am very concerned about their approach. They want to create a hot roof in the mold area using cellulose and Intello Plus barrier. I have more info on their approach but am keeping this super short so it's not marked as spam.
From what I'm reading this cellulose and vapor membrane combo is "risky". Am I right that spray foam is more fool proof? Also, what are the consequences of only addressing one part of the attic/crawl space? Would adding ventilation be a better course than trying to create a hot roof?
I would greatly appreciate any insight into the complexities of this situation. If you need more info on the construction of the house, etc., I can try to provide it. Thank you in advance
Posted Apr 9, 2017 12:18 PM ET
Edited Apr 10, 2017 6:43 AM ET
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