Crawl Space To Attic Ventilation

Get the right ventilation for your home.

Crawl space to attic ventilation.

Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. Before they removed the old insulation they looked inside it and found bits of bird nests. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. In december 2009 they released an exhaustive report about crawl space ventilation as it pertains to a variety of different climates across the country.

As indicated a vent from the crawl space to the attic would not be a wise thing to do. Researchers monitored two sets of new homes in different climates. Translated this code requirement means that you need 1 square foot of screened vent space penetrating the perimeter foundation for every 150 square feet of space in the crawl space. For example if your foundation size is 30 feet by 30 feet 900 square feet you will need vents that have combined square footage of 6 square feet.

Seal the vent off or either remove and seal the openings off. Before they sprayed the current code insulation they replaced the screens on all the vents and decontaminated the attic. One critical area of concern is moisture especially in attic and crawl spaces. Crawl spaces are still vented in most areas.

Even though crawl space vents are code in many areas the science behind the subject is now showing the complete opposite of the above statement. A 15 home modular housing development in hot humid baton rouge la. Intake vents located at the lowest part of the roof under the eaves allow cool. Encapsulating a crawl space eliminates these problems by bringing the crawl space into the building envelope and creating a dry healthy space.

Vents in the crawl space allow damp humid air to enter the crawl space where it will damage insulation and lead to mold growth. And 12 stick framed homes in cold dry flagstaff ariz. In the summer the warm highly humid air outside of the house is drawn into the colder less humid crawl space. Place 40 ft drainage pipe with holes across center floor of dirt crawl space attach this to duct line to attic space with an inline 90 cfm silent exhaust fan at the other end of attic run a 6 in.

The techs were focused on doing things the right way. There have been recent discussions here where if crawl spaces are not vented that they are made part of the building envelope. Duct through corner of closet from attic back to crawl to circulate dry attic air and close the foundation vents. Crawl space attic pro were recommended by a friend to whom i owe big thanks.