I have mold (black and grey types) growing on the ceiling along the exterior walls in various areas of my upstairs floor. It doesn’t extend into the room past 9 inches from the wall but it grows in the 4 corners predominantly, as well as in several other areas. The eaves drain to the 2 back corners which is where I first noticed the mold (I’m seeing it in the front corners and other areas as well now). I’ve removed the drywall on the ceiling and found the framing is fine and there isn’t any mold on the attic side of the drywall but the vapour barrier looks like it’s deteriorating heavily. The slope of the roof is very low so when I get into the attic I can’t get close to the area where the walls meet the roof, but there is insulation in the attic (I don’t recall seeing any baffles though). The house was built in 1982 and the mold only shows in the winter. Any ideas what’s going on and suggestions for replacing the vapour barrier without tearing the out the ceiling?
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Many thanks for any help.
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Since there’s been no reply.
Have you had this mold tested?
Mold maybe, but there’s another possibility.
In cold climates we’ve seen dark lines on walls at the stud locations. Usually not mold but “dirt “ in the air sticking to the cold studs. Often higher up as that’s where the heat and higher humidity sits.
Heavy smokers or dust etc add the particles while lots of plants or aquariums off gas the moisture which condenses at the cold stud locations.
What is your humidity reading and is there not much air movement in the rooms.
Tnanks for the reply Calvin, and sorry for the delay replying, I was taking your advice on checking the humidity. At the mold spots it was between 61-64% rh, and other areas were 58ish. The temp in our house is about 21C.
The air doesn't feel stagnant but some rooms will go hours without people in them but all rooms have vents.
I haven't had the mold tested but will look into it.
I didn't mention it before but the ceilings all have a popcorn finish-not sure if that matters.
Have you heard of a paint I could apply on the ceiling that's acts as a vapour barrier or something I could add to the attic? Would more insulation help in your opinion?
Thanks again for the help.
Here in NW Oh., comfortable percentage would be more like 38%rh.
Enough for some condensation on the bottom sash on cold nights.
Cold spots (studs and plates is where the “dirt/grime” collected) due to higher moisture content on cold surfaces. Interior temperature didn’t really make a difference.
I would non scientifically say that the same could happen with mold I guess.
There is paint they claim is a moisture “blocker” but I don’t know as to its mold “proof-ness”. The direct cold transfer blocking is your best bet. That and lowering that humidity. Do you have fish tanks or a lot of plants?
I think you're in a similar climate as i am (Ontario, Canada) so my moisture level should be similar to yours im sure. I have quite a few plants but we got rid of the aquarium last year. I've been running a dehumidifier which has helped but it fills up overnight so I started wondering if it would pull moisture into the house- probably highly unlikely. We had an energy audit done last April and moisture was brought up at that time as well. I think the house is "tight" or something along those lines. I was wondering if adding more insulation in the attic would help as unclemike42 mentioned so I think we'll try that and look into the paint.
Thanks again, you've been a big help. Cheers.
More insulation in the attic, above the wall, is going to reduce the heat loss in those upper corners. Baffles will help keep air circulation from eaves to vents above, and let the roof decking dry. This is also the first remedy for any ice dams.
If you cannot get to the edge of the attic, you may want to call in a local insulation contractor for an estimate.
There is also something going on with all that moisture in the house.
You can buy paint primer that is formulated to act as a vapor barrier.
Thanks Unclemike42. I'm going to look into renting a machine from Home Depot for blowing in insulation and see if I can take care of that and the baffles myself. Try to save money if possible. I'll do more research on the paint and see if it'll help. I'd really like to get rid of the popcorn ceiling before doing that though.
Take care.