Cbc Attic Ventilation Requirements

Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.

Cbc attic ventilation requirements.

Feet of attic space divided 50 50. 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. Ventilation air supply requirements for occupancies regulated by the california energy commission are found in the california energy code. That is openings doors windows and louvers to the outside should create a.

1 square foot of ventilation for each 150 square feet of attic space. Code requirements the international building 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. The net free ventilation shall be a minimum ratio of 1 150 of the area or space ventilated e g.

The chart below represents the net minimum area in square inches required for proper ventilation. Typically building codes include minimum requirements applicable to attic ventilation. 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. Occupiable spaces listed in table 402 1 shall be designed to have ventilation outdoor air for occupants in accordance with this chapter.

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. Enter square footage calculate or enter the square footage of the attic or area to be vented. 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. Attic ventilation cbc 1203 2 and crc r806 2 provide cross ventilation at all attic and enclosed rafter spaces.

Foot of ventilation for every 150 sq. Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. If your attic is enclosed california s building code states it should have cross ventilation. The roofing industry also has practical guide lines for attic ventilation.

Amendment also allows dsa. 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.