Required Ventilation In Attic

A discussion on attic ventilation isn t complete without going over the calculations to determine the minimum required net free ventilating area nfva.

Required ventilation in attic.

30 lineal feet required. 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. 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 following is an example shown in the irc commentary for a simple gable roof using the 1 300 ratio.

Of attic space 1 150 ventilation ratio measured at the attic floor level ceiling. Calculate or enter the square footage of the attic or area to be vented. Furthermore nrca also rec ommends the amount of ventila. Intake vents located at the lowest part of the roof under the eaves.

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator. 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. Most building codes require a ratio of 1 150 ventilation space to attic floor space.