We are in the final stages of a pier and beam home build in Dallas Texas.
Our hardwoods have cupped due to moisture from the crawl space. They have not been finished so we are waiting for them to dry. We did not place a poly vapor barrier on the dirt below the foundation when we built. The humidity is approx. 80-85% under the home now and 40% on the first floor . We have a vented pier and beam foundation however the soil remains moist like playdough..
How can we fix this post construction. Does anyone have a solution for us. should we place poly afterwards on the ground? Does it need to be dry first ?

This message has been edited. Last edited by: Frankm,

You're getting moisture BECAUSE you don't have a vapor retarder on the ground. Yes, you can and should place one now, using 6-mil polyethylene sheet, with joints lapped 6 inches and taped, and sealed at all walls and at all piers and other penetrations such as pipes and conduits. No need to wait for the ground to dry, because it probably never will dry. All the more reason why there should be a vapor retarder.

The crawl space should also have vents located 3 feet from the corners, totalling a minimum of one square foot of FREE AREA for each 150 square feet of floor area of the crawl space.

Question: My home smells musty when we walk in the front door and before i moved in the craw space at the front had a couple inches of water that was dried out with fans before i moved in. My son says at my house his sinus are worse. The landscaping in the front of the house is flat with small gravel and i wonder if sloping the landscape would help the water not sit and seep in there or do i need to lay a sheet of that plastic? I can't afford to have someone do it and wonder is that something we can purchase at Lowes or Home Depot and lay down ourselves if that is what we need to do??

The plastic film is to prevent moisture from the ground getting into your house. If you have standing water in your crawl space, you have water, not moisture, and you probably have a leak of some sort, either in the foundation wall or just above it. The cure can't be prescribed until the disease is diagnosed. Fortunately, you don't need a doctor...a garden hose will do. Read through the posts by LicensedWaterproofR to find the procedures for testing and repair of leaky foundations, and the many possible causes.