Air conditioned homes have floors that cooled below the dew point of the air in the crawlspace. Therefore moisture collects on the damp side of the subfloor and moves through to the home. As a result the wood is very damp. To reduce the moisture level in the crawlspace, the earth and water must be covered by a vapor barrier which could be plastic or concrete. If the summer outdoor dew points are the same or above the floor temperatures, the vents must be closed to prevent moisture entering the crawlspace. After closing the vents, monitor the % RH of the crawlspace. If the %RH is above 60%, dehumidification will be required.