Roof Venting Formula

11 12 roof pitch and higher increase the amount of ventilation by 30 percent.

Roof venting formula.

27 lineal feet required. Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. Length x width of attic in feet 150 total sq.

Ft divided by 150 equals 10 sq. Calculate the total vent area needed. Soffit vents allow outside air to. A 50 x 30 attic would have a total area of 1 500 sq.

The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. How to determine the number of attic vents. For projects involving vents with motors the calculation formula is different. 7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent.

One of the easiest and most effective ways of ventilation on a roof is to use a ridge vent. A ridge vent is installed at the peak of the roof where the hot air rises to. Proper air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials. 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.

Next divide that number by 2. Now you know how many square inches of attic roof venting you need for the roof and soffit. 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. Of total vent space needed.

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. 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. Ventsure 4 foot strip heat moisture ridge vent. Two square feet equals 288 square inches.

Choose one of the following products to meet the recommended exhaust nfva of 528 square inches.