Roof Ventilation Requirements

The key to proper ventilation of your roof and attic is balance.

Roof ventilation requirements.

Air space no less than 1 inch must be provided between any insulation or obstruction and the roof sheathing. You can also contact your local municipality to check on building code in your area. Most building codes require a ratio of 1 150 ventilation space to attic floor space. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.

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. Attic ventilation requirements how many attic vents your roof needs. Foot of ventilation for every 150 sq. Measure the length and width of the attic floor space to be ventilated.

R806 1 ventilation required 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. 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. The amount of space you devote to intake must be equal to the amount you allow for exhaust and these must be calculated according to the size of your attic and slope of your roof. The net free vent area nfva shall not be less than 1 150 of the area of the space being vented.

Ventsure 4 foot strip heat moisture ridge vent 27 lineal feet required. Blocking and bridging must be arranged so they do not interfere with air movement. Ventilation openings having a least dimension larger than 1 4 inch 6 4 mm shall be provided with corrosion resistant wire cloth screening hardware cloth perforated vinyl or similar material with openings having 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 between the inlets and outlets.