Climate Zone 3 subfloor encapsulation
I am renovating a 70 yr. old house in San Diego that I have owned for 5 years. It is Climate Zone 3 here. The original floors were 4×6 post and beam with 2×10 planks (no joists) and no insulation. The 2×10’s were spongy and kind of had a white’ish tint to them (maybe from years of salty air)?. So I gutted the entire subfloor which was ventilated at the rim boards and at the 2 accesses. The new floor system is 2 x 6 joists with 3/4” tongue and groove OSB. Initially, I was going to not insulate the floor and reinstall the vents at the rim boards. My main concern is the salty air causing a problem with the OSB subfloor and possibly leeching up into the laminate flooring. I am considering 1 1/2” closed cell spray foam on the bottom of the OSB and floor joists or encapsulating the crawlspace with by spray foaming the stem wall and installing a 12 mil vapor barrier product and install a LOMANCO unit. Encapsulating the crawlspace is about 70% cheaper. A spray foam contractor told me that encapsulating the crawlspace in this climate zone would be a big mistake and would definitely cause a mold issue in the subfloor area. I have been researching and looking into this for several weeks And I am leaning toward encapsulating the subfloor. For some reason I don’t know if I can believe him so I am looking for some input. I have a bout 18 to 24 inches of area to crawl so space is not a factor for the installation of spray foam. So the question is do I leave the OSB and floor joist as they are and then laid the crawlspace as it was? Or should I consider encapsulating the crawlspace or spray forming the underside of the floor deck? Thanks for your input.
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