Seal all the openings to the outside in all the crawlspace/basements after all exposed earth is covered. Even dry earth dumps a lot moisture in the space. This will change the overall humidity load on your home. Insulation above a sealed crawlspace agrevaites the humidity level between the insulation and subfloor because the subfloor is colder with the insulation. Lowering the temperature of subfloor 5^F raises the %RH 15%. Wood responds to %RH.
Originally posted by jesup
Thanks - IIt sounds like it makes most sense from here to repair/replace the floor insulation (sealing as I go) and dehumidify instead of trying to retrofit to modern (buildingscience.com) conditioned crawlspace.
You say close the vents - both crawls have old non-functional exhaust fans on timers, probably 18" diameter. I assume I'll need to seal those and also seal around penetrations (HP lines, some electric, etc).
I have two crawlspaces (ok, 3, but the other one stays bone-dry year-round, and is combined with a basement area that's alerady dehumidified). One is 550ish sq ft, the other is probably closer to 800. Both also have the HP air handlers and primary ducting. (One older installation; one rigid duct running the length with internal insulation (yes, evil) with flex runs to the vents at the outside walls, the other a new installation (Carrier dual-stage) with R5.x insulated rigid feeding R6 flex in the crawl, and feeding hard ducts in interior walls to the second floor. Hard-ducted returns.