Attic Air Ventilation Requirements

Balance is the key.

Attic air ventilation requirements. Hence you would need two square feet 600 300 of attic ventilation. Most building codes require a ratio of 1 150 ventilation space to attic floor space. What does the code require. 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.

As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. Basic attic ventilation principal is to keep that unused section of our house as cool as possible critical condition during the cold season dividing amount of the roof upper and lower vents 50 50. The insulation will resist heat transfer into the house. Building codes vary.

In the summer natural air flow in a well vented attic moves super heated air out of the attic protecting roof shingles and removing moisture. You can also contact your local municipality to check on building code in your area. The federal housing authority fha and the urban development hud have established minimum requirements for attic ventilation. Calculate or enter the square footage of the attic or area to be vented.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. There should also be a 50 50 balance of attic venting and roof venting. Measure the length and width of the attic floor space to be ventilated. I was told there would be no math.

Proper insulation and air sealing also keeps attics cold in winter by blocking the entry of heat and moist air from below. Does an attic have to be vented. According to the fha federal housing administration us for every 300 square feet of attic floor area you should have at minimum one square foot ventilation. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.

To lower attic temperatures and to remove excess moisture. Vents are rated by their net free area or the amount of space for air to flow in or out. Enter your square footage.