2012 Irc Attic Ventilation Requirements

According to the national roofing contractors association nrca a power vent with an airflow rate of 1 0 cubic foot per minute per square foot of attic space measured at the attic floor is generally considered to be equivalent to a 1 150 ventilation ratio.

2012 irc attic ventilation requirements. The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process. For large volume attics such as where roof slopes are greater than 8 12 designers also should consider increasing the amount of attic ventilation. Enclosed attics and enclosed rafter spaces formed where ceilings are applied to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain and snow. Nrca guidelines regarding attic ventilation nrca recommends designers provide at least 1 square foot of nfva for every 150 square feet of attic space 1 150 ventilation ratio measured at the attic floor level ceiling.