The installation of the aggregate base for the concrete slab in the crawl space is well underway. The grade beam and perimeter of the crawl space is insulated with insulation board. A unique aspect of the crawl space is the installation of the radon gas extraction system. The grey rectangular box currently laying on the rock will be covered with the concrete slab. A fan will draw rising soil gases thru the radon mat below the slab and expel the gases to the exterior of the building. This prevents radon gas from collecting in the crawl space.