Attic ventilation cbc 1203 2 and crc r806 2 provide cross ventilation at all attic and enclosed rafter spaces.
Cbc attic ventilation requirements.
The roofing industry also has practical guide lines for attic ventilation.
Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.
Feet of attic space divided 50 50.
Ventilation air supply requirements for occupancies regulated by the california energy commission are found in the california energy code.
Attic ventilation requirements how many attic vents your roof needs industry standard for proper attic ventilation recommends for no vapor retarder type of attic insulation no paper plastic or aluminum layer between the attic floor and insulation layer 1 sq.
Foot of ventilation for every 150 sq.
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.
Enter square footage calculate or enter the square footage of the attic or area to be vented.
1 square foot of ventilation for each 150 square feet of attic 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.
If your attic is enclosed california s building code states it should have cross ventilation.
Amendment also allows dsa.
The net free ventilation shall be a minimum ratio of 1 150 of the area or space ventilated e g.
Typically building codes include minimum requirements applicable to attic ventilation.
Code requirements the international building code.
The chart below represents the net minimum area in square inches required for proper ventilation.
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.
1203 3 the uniform building code requires enclosed attic spaces enclosed rafter spaces and under floor areas to be ventilated by not less than 1 square foot for each 150 square feet of attic under floor area.
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.
Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems.
That is openings doors windows and louvers to the outside should create a.
2016 cbc and the july 1 2018 supplement are being repealed and coadopted with oshpd.
