Raised floor over slab, musty insulation problem
About a year ago I built a small apartment inside part of a detached garage. I have been noticing a strong musty smell lately. The space is built on a raised floor about 8″ above the garage slab with a 6 mil vapor barrier over the slab and inside of the stem wall. I’ve tracked down the smell to the fiberglass batts I used to insulated the space between the slab and raised floor. I opened up part of the floor to investigate and haven’t found any visible mold, water or condensation. However the insulation smells really bad.
My plan is to tear up a strip of the flooring for access and pull out the smelly batts. I’m trying to avoid tearing up the entire finished floor. My idea was to just leave the floor uninsulated after removing the batts and use mechanical venting to bring conditioned air from the living space down through the mini crawl space and then exhaust it outside. My question is will this keep the uninsulated space under the floor dry and mold free or will I end up with condensation on top side of the poly barrier that is over the slab? Could I use a small HRV as the mechanical venting (the apartments is built very tight and gets a bit stuffy and humid as well)? That is have the have the HRV exhaust duct pull air through the under floor space and solve both the under floor issue and indoor air quality at the same time and minimize heat loss?
I’m on the border between climate zone 4C and 5B. Warm to hot dry summers and cold-ish wet winters. Heating is simple electric wall unit.
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