Venting a crawl space

July 25, 2022
How to Use Flood Vents to

There has been a great deal of debate on whether to vent or close a crawlspace. Vented crawlspaces worked great until the invention of air conditioning. When a family cools their home to 72° during the summer and the air outside is 85° with a 80% relative humidity, it creates condensation on the floor joist, the insulation and the pipes and ducts. No amount of ventilation will solve the problem at this point. This constant condensation during the summer months causes wood rot, mold, and attracts all types of insects including termites.

Closing a crawlspace (which includes sealing the vents, insulating the walls, creating a vapor barrier and conditioning the air in the crawlspace) is now the standard for LEED homes, NAHB Green homes and will probably be part of the building codes in the near future. The leading research on this subject was performed by Advanced Energy under a grant from The U.S. Department of Energy.

This research identifies the common symptoms of a crawl space moisture problem as:

  • 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

Closing the crawlspace creates a clean conditioned space under the home provides the following benefits:

  • Improves air quality throughout the home
  • Saves up to 18% in heating and cooling cost in the Southeast
  • Reduces mold and wood decay on floor joist
  • Reduces buckling of hardwood floors
  • Creates warmer floors in the winter
  • Reduces pest and termite pressure

Over 76 million homes in the US are currently built on crawlspaces. 18% of all new homes built in the US are built on crawlspaces. Our goal at Crawlspace Depot is to significantly improve families' quality of life, save them millions of dollars in energy usage and make the job of maintaining pest-free homes easier. Please give us a call to find out more about closed crawlspaces and our line of crawlspace products.

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