Roof Ventilation Requirements

Most building codes require a ratio of 1 150 ventilation space to attic floor space.

Roof ventilation requirements.

Ventsure 4 foot strip heat moisture ridge vent 27 lineal feet required. The key to proper ventilation of your roof and attic is balance. Blocking and bridging must be arranged so they do not interfere with air movement. You can also contact your local municipality to check on building code in your area.

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. You can calculate attic ventilation requirements by determining the square footage of your attic floor its width times its length and compare that to the total required net free area nfa. 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.

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. Air space no less than 1 inch must be provided between any insulation or obstruction and the roof sheathing. Roof vents choose one of the following products to meet the recommended exhaust nfva of 528 square inches. Attic ventilation requirements how many attic vents your roof needs.

The net free vent area nfva shall not be less than 1 150 of the area of the space being vented. Measure the length and width of the attic floor space to be ventilated. 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. Foot of ventilation for every 150 sq.