Traditional crawlspaces are vented with the idea being that the outdoor air will circulate enough in the crawlspace to maintain desired relative humidity levels over time. The unfortunate truth is that we leave in the southeast and our climate is very humid much of the year. This coupled was crawlspaces being low to the ground and things such as duct work and other items blocking the already poor humid air floor results in elevated relative humidity and in turn problems such as wood rot, air quality issues, mold, and pest issues.
The best way to control humidity issues in a crawlspace is through a properly installed crawlspace encapsulation. Crawlspace encapsulations are made up of the following characteristics:
- Closing off and insulating all foundation vents
- Installing a durable vapor barrier on the floor of the crawl space
- Wrapping the foundation walls and piers with a vapor barrier
- Sealing ALL seams in the vapor barrier with seam tape
- Sealing ALL plumbing and/or electrical items that enter through a floor or wall with insulation
- Installing a system to control the relative humidity – dehumidifier
- Installing a new insulated door if existing door is not already insulated
When a crawlspace is properly encapsulated the homeowner will see the average relative humidity of a crawlspace fall below 60 percent. The ideal relative humidity for a crawlspace is between 45 percent and 60 percent.