The ventilation amount and opening size requirements can be found in section 806 roof ventilation of chapter 8 roof ceiling construction.
Roof ventilation requirements.
The following are the requirements taken directly from the irc.
R806 1 ventilation required enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow.
Feet of attic space divided 50 50 between the inlets and outlets.
Measure the length and width of the attic floor space to be ventilated.
Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.
The majority of the requirements related to attic ventilation have not changed much from the previous editions.
Roof vents choose one of the following products to meet the recommended exhaust nfva of 528 square inches.
Most building codes require a ratio of 1 150 ventilation space to attic floor space.
Foot of ventilation for every 150 sq.