Required Ventilation In Attic

Furthermore nrca also rec ommends the amount of ventila.

Required ventilation in attic. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. The following is an example shown in the irc commentary for a simple gable roof using the 1 300 ratio. A discussion on attic ventilation isn t complete without going over the calculations to determine the minimum required net free ventilating area nfva. 30 lineal feet required.

Most building codes require a ratio of 1 150 ventilation space to attic floor space. 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. Calculate or enter the square footage of the attic or area to be vented. 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.

For large volume attics such as where roof slopes are greater than 8 12 designers also should consider increasing the amount of attic ventilation to account for the additional volume of attic space. 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. You can also contact your local municipality to check on building code in your area.