Foundation Homes with crawl spaces are nearly always equipped with screened openings to provide cross ventilation of subfloor areas. Closing these vents is generally an unwise practice. The purpose of foundation vents has little to do with temperature control or energy conservation and is, therefore, unrelated to variations in weather. The primary purpose of foundation vents is to prevent moisture condensation on surfaces beneath the building. Therefore, open vents during wet winter months are essential. Closing your foundation vents during the winter is an invitation to condensation and resultant moisture damage, dry rot, and mold. Click here for helpful information on mold and mold remediation. Foundation vents should remain open at all times, especially during winter. Notwithstanding any further evaluations by a foundation professional as might be recommended in Section 3 – Areas of Concern, or any repairs by seller and/or buyer, it is imperative that foundations be kept as dry as possible to help minimize deterioration. Any irrigation by sprinkler system must be minimized so that overwatering does not occur. Gutters and downspouts should be installed and/or maintained to help direct rainwater from the roof to areas away from the foundation. Plumbing components in the crawl space must be monitored at least annually to detect any leaks.