Dehumidifiers or fans should be used in the crawl space to prevent the air from reaching above 45% relative humidity (RH). The gold standard for a crawl space is 60F degrees and 45% RH consistently. This generates a dew point of around 39F.

Dew point is very easy to control with spray foam as your insulator. Spray foam also minimizes the condensation of water pipes and tanks and help maintain an overall dry environment.