Closed crawlspaces, also called unvented, conditioned, or sealed crawlspaces, are dry, energy-efficient, practical options for single-family new construction—but they are a relatively new construction practice. To help builders more readily incorporate closed crawlspaces into their homes, the Home Innovation Research Labs, in partnership with the Southern Forest Products Association, created educational materials that include a downloadable TechSpec and a four-part instructional video series—all are available online at no cost.

The TechSpec, titled “Closed Crawlspaces: Making the Transition” (, is an easy-to-read summary that addresses the benefits and key steps for improving existing closed crawlspace design and construction practices, and transitioning from traditional slab-on-grade or conventional vented crawlspace construction. The TechSpec highlights the following benefits of closed crawlspaces:

• Dryness and durability produced as a result of the insulation, air sealing, moisture-control measures, and conditioned air.

• Marketability as raised wood-floor homes provide architectural appeal and a warm, comfortable walking surface.

• Applicability for sloped and infill sites, and challenging soil conditions.

• Simplified scheduling of trades and inspections.

• Improved whole-house energy efficiency because closed crawlspace temperatures are more stable compared with an attic or a vented crawlspace, and because locating ducts and mechanical equipment in the space reduces heating and cooling loads.

• Simplified installation of mechanical systems provides access for installation and maintenance, and allows for changes to floor plans.

• Limited learning curve for trades because of the use of familiar materials and methods.

The TechSpec also addresses code considerations, best practices, foundation walls, height and access, wood floor framing, moisture management, air sealing, insulation, and mechanical systems. The information presented is consistent with the 2012 International Residential Code (IRC) and is focused on warm and mixed-humid climate regions (climate zones 3A and 4A).

This resource bundle also includes four instructional videos ( that walk builders through the stages of closed crawlspace construction and address specific hot spots in greater detail. The online videos look at sealing the ground vapor retarder to the wall, installing wall insulation, ventilation, and how to build a closed crawlspace in climate zones 3A and 4A.

For more information on this construction technique or the educational materials, visit