Closed-cell spray foam insulation is applied to the foundation walls leaving a 2-inch viewing strip at the top of the foundation wall for termite inspectors, per Virginia Building Code. Now that we're keeping as much air as possible out of the crawl space, we need to control the relative humidity. This is achieved by installing the Sanidry Sedona Dehumidifier. This unit will pull excess moisture from the air, filter the air, and circulate dry air throughout the crawl space.