Crawl Spaces

Many homes built on crawl space foundations in the Southeastern United States suffer from poor moisture management. Some of the common symptoms of a crawl space moisture problem are:

  • Mold or moisture damage in the crawl space or living area
  • Musty odors in the living area
  • Condensation ("sweating") on air conditioning ductwork or equipment
  • Condensation on insulation, water pipes or truss plates in the crawl space
  • Buckled hardwood floors
  • High humidity in the living area
  • Insect infestations
  • Rot in wooden framing members

These symptoms are most often noticed in the humid spring and summer seasons but can occur at any time of the year. Often, the heating and air conditioning contractor is the first person the residents call to deal with the problem. Typically though, the problem is not due to a failure of the air conditioning system; it results from poor moisture control in the crawl space.

For many decades, building codes and conventional wisdom have prescribed ventilation with outside air as the primary method of moisture control in crawl spaces. In the humid Southeast, however, ventilation with outside air only makes moisture problems worse. Recent research by Advanced Energy and others indicates that a new type of crawl space system, with NO vents to the outside, can provide greatly improved moisture control and significant energy savings when properly installed.

This page lists materials and information generated by Advanced Energy research projects, diagnostic investigations and collaboration with a variety of professional installers and consultants across the country. We hope this information can help you to improve your existing crawl space or to design and install a properly-closed new crawl space.

Written Recommendations
Closed Crawl Spaces: A Quick Reference for the Southeast
The quick reference summarizes the design elements and installation steps that are discussed in the full 75-page guide below. The quick reference also includes two example designs from the guide.

Closed Crawl Spaces: An Introduction for the Southeast
This 75-page guide is an introductory reference to crawl space issues:

  • Design and implementation recommendations for closed crawl spaces
  • Four sample closed crawl space designs and a sample construction sequence
  • An overview of NC residential code requirements and issues
  • Recommendations for improving existing wall-vented crawl spaces
  • A summary of Advanced Energy's crawl space research results
  • Answers to frequently asked questions about mold in crawl spaces

  You may purchase a wire-bound copy of the introductory reference, along with laminated copies of the quick reference sheets, for $45 by clicking here. You may also send the pdf versions available here for download to your local printer for duplication, as they are of sufficient resolution for high quality reproduction.

Published Articles
"Closing the Crawl", Builder Magazine, October 2005
"Closed Crawl Spaces Do Double Duty," Home Energy, January 2005
"Crawl Space Mold Liability or Business Opportunity," Pest Control Technology, June 2003
"Double Duty," Pest Control Technology, October 2004
"To Vent or Not To Vent," Professional Remodeler, September 2004

Products and Suppliers
Links to the manufacturers of products or providers of services utilized in Advanced Energy research projects or discussed in the crawl space guide.

North Carolina Residential Building Code
The NC Building Code Council adopted new code language in September 2004 for both wall-vented and closed crawl spaces. The new language was approved by the legislative rules review process in November 2004. Click here and go to sections R408 and R409 for more detail.

Video Overviews
These short videos provide a short guided tour of crawl space issues and Advanced Energy's Princeville research project.

Technical Reports
Detailed reports of research goals, methods, results and conclusions that have been created per the contract requirements of Advanced Energy crawl space research sponsors and funders.

Additional Online References

Previously published research documents or other publications that may still be of use.

Research report available:
Closed crawl space performance in cold and hot-humid climates