Sealed and Conditioned Crawlspaces

Sealed and Conditioned Crawlspaces: Enhancing Efficiency and Comfort

Traditional vented crawlspaces, common in homes built over the last 30 years, often lead to energy inefficiencies and discomfort. These spaces, elevated above ground level, were initially designed with vents to minimize moisture from the soil. However, this design has significant drawbacks.

Fiberglass insulation, typically used in these crawlspaces, fails to effectively block air infiltration. Its imperfect fit allows for external air to penetrate, resulting in colder floors in winter and warmer, humid conditions in summer. Moreover, the presence of heating and cooling ducts in these crawlspaces exacerbates the issue, as they carry air at temperatures contrasting the outside environment, leading to inefficiency and ductwork sweating.

A Sealed and Conditioned Crawlspace is the optimal solution to these problems. By sealing off all external vents, it prevents outside air infiltration. The process involves laying a vapor barrier on the crawlspace floor, extending and securing it up the walls to block moisture from the soil. Conditioning the space by introducing heated or cooled air from the HVAC system maintains a consistent temperature, akin to the home’s interior. This approach significantly reduces moisture and humidity, enhances the efficiency of the heating and cooling systems, and ultimately saves money and future maintenance issues.

The Process of Creating a Sealed Crawlspace:

1. Laying a 15 mil vapor barrier on the crawlspace floor, extending 6-12 inches up the wall.
2. Securing the vapor barrier to the walls with concrete nails.
3. Applying open-cell spray foam up to 3 inches from the floor to the top of the band board, achieving an R-10 value, while leaving a 2-inch gap for termite inspections.
4. Sealing all overlaps and piers with tape.
5. Installing a baffled air register to supply conditioned air, calibrated to 50 cfm per 1000 square feet of crawlspace.

Benefits:

• Eliminates air infiltration by sealing walls, vents, and band board.
• Increases thermal resistance with spray foam on walls and band board.
• Reduces moisture intrusion through a strategically laid vapor barrier.
• Reduces humidity and stabilizes temperature by conditioning the space.
• Enhances energy efficiency, allowing air ducts to function in a consistent temperature environment.

Sealed and Conditioned Crawlspaces are not just cost-effective; they are a step towards a more comfortable, efficient home.