The builder mentioned that thefoundation had "all new insulation and pea gravel with vapor lock put down to code."

All that to say when evaluating NNN leased assets make sure you are comfortable on the ability of the property to be leased if the current users is to leave at lease expiration, we have all seen the poorly located former Hardee's or Wendys that is now a vapor store etc. 

Verify concrete dryness in accordance with ASTM F 1869 “Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride” (moisture vapor transmission should not exceed three pounds per 1,000 square feet in a 24 hour period), F 2170 “Standard Test Method for Determining Relative Humidity in Concrete using in situ Probes” (relative humidity should not exceed 80%), or D 4263 “Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method” (no moisture present).

We then had to pull about 10 truck loads of trash out from the crawl of one building, and do some minor repair underneath for plumbing, subfloor and installed new vapor barriers for both units.

We then had to pull about 10 truck loads of trash out from the crawl of one building, and do some minor repair underneath for plumbing, subfloor and installed new vapor barriers for both units.

The places I have used foam are things like crawl spaces or the underside of porches to insulate and vapor seal to prevent pipes from freezing. 

so I have a house under contract, this is for my primary residence in rock hill sc that I intend to house hack, and in my due diligence period the inspector found evidence of powder post beetles and extremely high moisture under the house and I'm wondering what this could end up costing me if i get it treated and have a vapor barrier put into the house and put up gutters to get this house to qualify for the loan and then it proves the damage is a lot deeper than inspected like into the sub floor i included some pictures to show the damage the inspector found  still have a week and a half till my due diligence is up (2/26/19)the really wet part is the beam at the front of the house around where the front door is 

I would seriously consider putting down a vapor barrier, 3/4" plywood, a vapor barrier and LVP.

Fibermesh only is fine, just make sure no matter what they do, whether it's rebar or fibermesh, that they put a poly vapor barrier down and pour on top of that.

This acts as a good vapor barrier at the same time.