Roof Venting Formula

So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements.

Roof venting formula.

For projects involving vents with motors the calculation formula is different. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find the total square feet of vent space 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. 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.

Choose one of the following products to meet the recommended exhaust nfva of 528 square inches. One of the easiest and most effective ways of ventilation on a roof is to use a ridge vent. A 50 x 30 attic would have a total area of 1 500 sq. A ridge vent is installed at the peak of the roof where the hot air rises to.

11 12 roof pitch and higher increase the amount of ventilation by 30 percent. Soffit vents allow outside air to. How to determine the number of attic vents. Next divide that number by 2.

27 lineal feet required. Up to 6 12 roof pitch use the standard formula as explained in this article. Two square feet equals 288 square inches. 7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent.

Now you know how many square inches of attic roof venting you need for the roof and soffit. Ventsure 4 foot strip heat moisture ridge vent. Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier. 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.

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. Length x width of attic in feet 150 total sq. A normal metal pot vent produces only 50 squares inches of free net area. Ft divided by 150 equals 10 sq.

Calculate the total vent area needed.