Residential buildings require roof ventilation, according to the International Residential Code, which is the legal building standard used throughout most of the United States. Enclosed attics and rafter spaces must have cross-ventilation for each separate space. However, code officials may grant exceptions based on climate and atmosphere conditions.
There should be at least 1 square foot of free vent area per 150 square feet of attic floor, the National Roofing Contractors Association advises.
However, building standards vary regionally, as the United States does not have a national building code. The codes created by the International Code Council, including the International Residential Code, are the most-used model codes in the country, according to the Environmental Protection Agency.