(I'm in Canada, which is generally a 'basement using' zone.) > In theory vapor accumulation is only really problematic in the overhead plenum spaces. In actual

(I'm in Canada, which is generally a 'basement using' zone.) > In theory vapor accumulation is only really problematic in the overhead plenum spaces. In actual practice (setting aside acute water ingress) 100% of the time moisture problems start in the crawl space and then spread to the plenum. Which is a good argument for conditioned crawl spaces. * https://www.buildingscience.com/documents/bareports/ba-0401-conditioned-crawlspace-construction-performance-and-codes/view https://www.buildingscience.com/documents/bareports/ba-0401-...