Eave Vent Area To Floor Square Ft Ratio

That determines the total amount of net free area needed to properly ventilate the attic.

Eave vent area to floor square ft ratio.

See how simple that was. Determine the total net free area required. Ok so now we know the square footage of the attic area to be ventilated. Remember the minimum area requirement when using a continuous system is a ratio of 1 300.

150 6 6 square feet of total net free area 3. A 6 x 12 vent would equal 72 sq. Now let s figure out how much ventilation space we need. 40 x 25 1 000 square feet of attic area 2.

1 square foot of nfva per 300 square feet of attic floor if a vapor barrier is installed on the ceiling below. This ratio is required for modern insulated homes. Most local building codes require compliance with either the 1 150 method or the 1 300 method exception refer to local code. In divided by 144 equals an area of 0 5 sq.

These methods dictate that one 1 square foot of ventilation is provided for every 150 or 300 square feet of attic floor space. So in our example we will divide the 1 500 square feet by 300. Divide the square footage by 150 to calculate the area of ventilation needed since you need 1 square foot of vent space for each 150 square feet of attic space. Once attic square footage is known divide by 150 for the 1 150 ratio.

30 feet x 50 feet 1 500 square feet. 1 500 square feet 300 5 square feet. If you have 3 000 square feet of attic space this equates to 20 square feet of ventilation needed.