How to Fix a Damp Crawl Space: Insulation, Sealing, and Drainage Tips
By Graham Mann | Published: 12/27/2025
Stop crawl space moisture with vapor barriers, moisture-resistant insulation, and proper drainage to prevent mold, rot, and high energy bills.
How to Fix a Damp Crawl Space: Insulation, Sealing, and Drainage Tips A damp crawl space can damage your home's structure, increase energy bills, and harm indoor air quality. Moisture leads to rotting wood, mold growth, and higher heating or cooling costs. Here's how you can address it: - Identify Moisture Problems: Look for musty smells, standing water, mold, or sagging wood. Use tools like a hygrometer to measure humidity (keep it under 60%). - Fix the Causes: Ensure proper drainage by fixing sloping yards, clogged gutters, or plumbing leaks. Seal crawl space vents and cracks to block humid air. - Insulate Properly: Use moisture-resistant materials like closed-cell spray foam or rigid foam boards. Avoid fiberglass, which absorbs water. - Install a Vapor Barrier: Lay thick polyethylene sheeting on the crawl space floor and seal it to walls to block ground moisture. - Add Drainage Systems: Use interior French drains and sump pumps for high water tables, and improve exterior grading to ...
← Back to all articles