Square Footage Of Vent For Roof

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

Square footage of vent for roof.

In cases where a roof has a complex shape such as in the image to the right measuring the dimensions and areas of each part of the roof to calculate total area will result in a more accurate measurement of area. Ventsure 4 foot strip heat moisture ridge vent. Of net free area of intake needed at or near the soffit. There are also gable and roof fans which actively pull the hot air out of the attic.

For the 1 150 attic ventilation requirement simply double the amount of exhaust and intake calculated. Vent roofs with steeples towers or cupolas can be found in different buildings from barns to cathedrals. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. Ridge static attic vents 384 00 minimum sq.

Choose one of the following products to meet the recommended exhaust nfva of 528 square inches. If there is no vapor barrier double it to one square foot of nfa for every 150 square feet of attic floor space half for intake half for exhaust. Calculate or enter the square footage of the attic or area to be vented. 6 measure the radius of round vents or take half the diameter of the.

Pick out your soffit vent size and determine the square footage of the vent. The building codes and building science for. Attic square footage 2 square inches of exhaust and square inches of intake net free area nfa needed. 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.

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. For example a 6 by 12 inch soffit vent has 72 square inches which when divided by 144 results in a 0 5 square foot opening. 27 lineal feet required. If your attic floor has a vapor barrier you will need one square foot of nfa per every 300 square feet of attic floor area half of that will be intake half for exhaust.

The calculator cannot account for complex shapes based on a measurement of square footage alone. Ventilation manufacturers assign an nfa value to the non motorized vents they make. For example if you use 16 inch by 8 inch soffit vents each vent is 128 square inches. Divide this by 144 to calculate how many square feet each vent is.

Of net free area of exhaust needed at or near the ridge.