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.

11 12 roof pitch and higher increase the amount of ventilation by 30 percent. Next divide that number by 2. The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. Ft divided by 150 equals 10 sq.

Of total vent space needed. Up to 6 12 roof pitch use the standard formula as explained in this article. 27 lineal feet required. 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.

7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent. A normal metal pot vent produces only 50 squares inches of free net area. Now you know how many square inches of attic roof venting you need for the roof and soffit. Proper air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials.

Calculate the total vent area needed. Choose one of the following products to meet the recommended exhaust nfva of 528 square inches. A 50 x 30 attic would have a total area of 1 500 sq. 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. How to determine the number of attic vents. 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. One of the easiest and most effective ways of ventilation on a roof is to use a ridge vent.

Two square feet equals 288 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. A ridge vent is installed at the peak of the roof where the hot air rises to.

Soffit vents allow outside air to.