1 150 Attic Ventilation

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.

1 150 attic ventilation.

Ft of attic space 1 square foot of ventilation is recommended. This is based principally on good historical experience and simple psychrometric analysis handegord giroux 1984. 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. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

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. Ok to determine how much ventilation area you need for your house all you need to know is the square foot area of the attic to be ventilated. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

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. 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. The house measures 30 feet by 50 feet. Owens corning recommends a balanced ventilation system based on the u s.

No soffits means 1sq ft 144 sq inches of venting for every 150 sq ft of attic space if soffit venting is there 1sq ft 144 sq inches venting per 300 sq ft. 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. The recommended ventilation ratio to provide for vented attic assemblies when an air barrier is present is the 1 300 ratio as specified by most building codes. For every 150 square feet sq.

When you purchase vents check the square inches for those vents they range from 38 49 or as high as 100 inches per vent so do the math. Let s use the following simple ranch house for an example.