Attic Ventilation Requirements California

Attic or rafter space.

Attic ventilation requirements california.

Always have a balanced ventilation system. If your attic is enclosed california s building code states it should have cross ventilation. Gables to be insulated as exterior walls. The chart below represents the net minimum area in square inches required for proper ventilation.

Mandatory minimum r 22 attic insulation unvented attics must be air sealed at roof deck eaves gables and penetrations. In no case should the amount of exhaust ventilation exceed the amount of intake ventilation. Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum. 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.

If installed above the roof they shall be located 18 inches 457 mm above roof level or 3 feet 914 mm above a flat roof where heavy snowfall is anticipated. 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. Chapter 7a says that vents must resist the intrusion of embers and flames or that they shall be protected by corrosion resistant noncombustible wire mesh screen with openings. Ventilators located in the upper portion of the.

1 8 mesh is also allowed. Air handler ducts in attic vented or unvented compliance must be demonstrated via energy modeling with cbecc res software. 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. So mechanical ventilation is now required in california to improve indoor air quality in all new residential construction when alterations are made to a residence and in residential additions of 1 000 sq ft or greater.

Area shall be 1 300of the vented space provided. 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. That is openings doors windows and louvers to the outside should create a natural flow of fresh. The required ventilating area is provided by.

Three frieze block vent holes can be seen in one section of blocking. Upper ventilators sha ll be. No less than 40 and not more than 50 of.