Obviously he’s paying for all the flooring repair costs since he didn’t test the humidity.

I’m in savannah Georgia so a similar climate. How is your crawlspace finished currently? Just dirt? Vapor barrier loose on the surface? Completely sealed with vapor barrier up the walls?

Best practices for remedying wet crawl spaces are well documented; see https://www.jlconline.com/how-to/insulation/fixing-a-wet-crawlspace_o In our mixed-humid (coastal VA) climate,

I find that supplying conditioned air from the living space at a rate of 1 cfm/50 SF of living area obviates the need for a dehumidifier, provided there is an adequate soil moisture vapor retarder in place and storm water is appropriately managed to direct it away from the foundation.

@hallett currently 6mm vapor barrier on the ground only, over gravel

CR Homes, how to supply conditioned air to crawlspace without resulting in negative pressure in the structure interior? Surely you don't put a return in the crawlspace?

@Elmer,

I've been building homes with "unvented" (sealed, conditioned) crawl spaces since 1999--long before they were allowed by prescriptive code. I don't know where the adults were when the prescriptive code requirements were written for unvented crawl spaces. Section 408.3 of the 2108 IRC requires a return air path for air supplied to the crawl. The last thing you want to do, in my opinion, is to introduce air that's been in the crawl space back into the living area. I don't do it. I'd rather live with the modest negative pressure resulting from continuous air flow from the living space to the crawl. Let's do some numbers: Let's say a home constructed over an unvented crawl space has 2,500 SF of living area. The required ventilation rate for the "unvented" crawl is 1 cfm per 50 SF of living area. 2,500/50 = 50 cfm. That's the flow rate you expect from a powder room vent fan in a cheap townhouse. If the ceiling height in the living space is 9 ft. , then the indoor air volume is 2,500 x 9 = 22,500 cubic ft. The 50 cfm flow rate would result in a single air change in 450 minutes (7.5 hours) By contrast, the maximum allowable air infiltration rate per code in my climate zone is 3 air changes per hour at 50 Pa differential (ACH50) which is a total of 22.5 air changes in the same 7.5 hour period. I can live with that.

E.T.A. The above calcs are for a single-story 2,500 SF home. The flow rate is based on the area of the crawl.