Purpose

• Crawl spaces must be ventilated in order to allow water vapor to escape. If water vapor cannot escape, it can damage wood structures and seep up into the home. Once inside the home, the excess moisture can cause mold and mildew growth, wood rot, and the peeling of wallpaper and paint.
  
  

Specifics

• Crawl spaces should be ventilated with standard metal foundation vents, which are generally 8 by 16 inches. These vents should be placed within the top 8 inches of the metal foundation and should equal at least 1 square inch of unobstructed ventilating area for each square foot of crawl space area. It is important to make sure that each corner of the crawl space has a vent to allow for air flow throughout the crawl space.
  
  

Additional Considerations

• Vents in your crawl space should remain open all year, with the exception of the coldest days. To prevent moisture problems, you should consider installing a vapor barrier in addition to the ventilation.