Ventilation Reference for New Homes

1 to 150 square feet free ventilation ratio in attics and crawl spaces where no vapor barrier exists
1 to 300 square feet free ventilation ratio in attics with vapor barriers and crawl spaces
Use baffles
Mechanical ventilation should be provided in kitchens, bathrooms, and utility areas. Fans should be sized to ensure proper flow for the square footage of the area. All vent connections should be sealed and the pipe kept reasonably straight to an exterior exhaust. Your HVAC contractor may offer whole-house solutions for venting. N. C. energy code requires minimum exhaust levels of 50 cfm for bathrooms / 100 cfm for kitchens.