Attic Air Ventilation Requirements

Does an attic have to be vented.

Attic air ventilation requirements.

Hence you would need two square feet 600 300 of attic ventilation. What does the code require. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Calculate or enter the square footage of the attic or area to be vented.

There should also be a 50 50 balance of attic venting and roof venting. 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. 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. Enter your square footage.

To lower attic temperatures and to remove excess moisture. Proper insulation and air sealing also keeps attics cold in winter by blocking the entry of heat and moist air from below. As an example in an attic that is 30 feet by 20 feet you would have 600 square feet of floor area. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space.

I was told there would be no math. 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. Vents are rated by their net free area or the amount of space for air to flow in or out. In order to facilitate this exchange of warm and cool air the general rule of thumb suggests installing at least 1 sq.

Most building codes require a ratio of 1 150 ventilation space to attic floor space. Measure the length and width of the attic floor space to be ventilated. The insulation will resist heat transfer into the house. You can also contact your local municipality to check on building code in your area.

Balance is the key. The federal housing authority fha and the urban development hud have established minimum requirements for attic ventilation. Attic ventilation serves two main functions.