Roof Venting Formula

Soffit vents allow outside air to.

Roof venting formula. 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. Ft divided by 150 equals 10 sq. 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 air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials.

11 12 roof pitch and higher increase the amount of ventilation by 30 percent. Ventsure 4 foot strip heat moisture ridge vent. Next divide that number by 2. Two square feet equals 288 square inches.

One of the easiest and most effective ways of ventilation on a roof is to use a ridge vent. Choose one of the following products to meet the recommended exhaust nfva of 528 square inches. 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. 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.

Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier. How to determine the number of attic vents. A ridge vent is installed at the peak of the roof where the hot air rises to. Now you know how many square inches of attic roof venting you need for the roof and soffit.

A normal metal pot vent produces only 50 squares inches of free net area. A 50 x 30 attic would have a total area of 1 500 sq. Length x width of attic in feet 150 total sq. Up to 6 12 roof pitch use the standard formula as explained in this article.

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

Calculate the total vent area needed.