I recently bought a house with a dirt crawl space (basement). The crawl space had lots of old wood, moisture, organic debris and high levels of penicillium aspergillus mold. In order to remediate this problem, I removed all scrap wood and the debris and encapsulated the crawl space by putting down plastic on the floors and up the foundation walls, then had the crawl space spray foamed from the rim joist down to the plastic. On the first floor of the house, I removed layers of lineolum and carpet and had the old yellow pine floors refinished. Unfortunately, there are large gaps between the floor boards with nothing underneath and the air from the crawl space can pass directly into the house.
I want to put something on the ceiling of the crawl space to keep the crawl space air and dust from going into the house, but if I put plastic on the ceiling of the crawl space, the entire space will be totally encapsulated in unbreathable material which seems wrong. Should I put up paper to filter the air or tyvek? Is this a common situation in old houses? I live in coastal Maine, where it is both damp and often cold.