Up to 40% of the air in your home comes from the crawl space. If that air is traveling through unsealed gaps, rim joists, and utility penetrations, you're paying to heat and cool the outdoors — and breathing whatever's under your house.
Homes breathe. Warm air rises and escapes through the upper floors and attic, creating negative pressure at the bottom of the house. That negative pressure pulls in replacement air from the crawl space — through every crack, gap, and unsealed penetration it can find. This is called the stack effect, and it means:
Air sealing attacks this problem at the source — stopping the air before it ever enters your living space.
Air sealing isn't glamorous work, but the energy and air quality payoff is significant. Here's what we address on every job.
The single largest source of air infiltration in most crawl spaces. We seal rim joists with closed-cell spray foam for maximum R-value and air barrier performance.
Every pipe, wire, duct, and conduit that passes through the floor or foundation is sealed with appropriate materials — foam, caulk, or metal collars.
Open or damaged foundation vents are sealed with rigid foam inserts or replaced entirely with sealed covers as part of a conditioning strategy.
Disconnected or leaking duct connections in the crawl space are sealed and strapped — stopping conditioned air from escaping before it reaches your living space.
Gaps between the subfloor and framing — common in older homes — are filled or covered as part of a comprehensive air barrier strategy.
The access door perimeter is gasketed and weatherstripped so it seals airtight when closed, just like an exterior door should.
Insulation slows the transfer of heat. Air sealing stops air from moving through gaps entirely. Both are important, but air sealing is often more impactful per dollar — especially in older homes where gaps have developed over decades of settling.
Yes. We can coordinate blower door testing before and after air sealing work to document the improvement in ACH (air changes per hour). This is particularly useful for energy rebate programs.
It can, if not done correctly. That's why we always pair air sealing with a moisture management strategy — typically a dehumidifier and vapor barrier. A sealed, dry crawl space is the goal. A sealed, wet one is worse than before. We won't do one without the other.
Often yes. Air sealing qualifies for the federal 25C energy efficiency tax credit (up to 30% of costs) and many Tennessee utility companies offer rebates for verified air sealing work. We'll provide documentation needed for any rebate program.