DIY Crawl Space Guide: Air Sealing Subfloor: Week 6

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Your crawl space might be the most overlooked yet critically important area of your home. In this sixth installment of the Crawl Space Repair Challenge, Michael Church tackles the crucial topic of air sealing—a process that dramatically improves energy efficiency, indoor air quality, and structural integrity.

The Department of Energy confirms what Michael has seen firsthand: unsealed crawl spaces contribute significantly to moisture problems affecting both your health and home structure. When air freely moves between your crawl space and living areas, it brings along unwanted moisture, allergens, and even radon. Through detailed demonstrations, Michael walks you through the why and how of comprehensive air sealing, identifying 19 different areas throughout your home requiring attention.

From foundation walls to subfloors and ductwork, every potential air leak creates problems. Michael reveals that an astonishing 25% of conditioned air moving through unsealed duct systems simply leaks away—wasted energy you're paying for each month. Using professional-grade materials like mastic spray, foam sealants, and specially formulated concrete crack repair kits (originally developed for NASA), he demonstrates exactly how to create an effective air barrier. The techniques shared work equally well in crawl spaces, basements, and even more visible areas of your home.

Whether you're a dedicated DIY enthusiast or simply want to understand what professionals should be doing in your crawl space, this episode delivers actionable advice to transform your home's forgotten foundation into a properly sealed, energy-efficient space. Ready to stop wasting energy and improve your home's air quality? Watch now, then grab your caulk gun and join the thousands who've already completed the Crawl Space Repair Challenge!

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