Roof Venting Formula

Two square feet equals 288 square inches.

Roof venting formula.

A 50 x 30 attic would have a total area of 1 500 sq. Ventsure 4 foot strip heat moisture ridge vent. Soffit vents allow outside air to. Ft divided by 150 equals 10 sq.

Next divide that number by 2. 27 lineal feet required. For projects involving vents with motors the calculation formula is different. 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.

Now you know how many square inches of attic roof venting you need for the roof and soffit. 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. So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements. 11 12 roof pitch and higher increase the amount of ventilation by 30 percent.

How to determine the number of attic vents. 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. Length x width of attic in feet 150 total 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. Calculate the total vent area needed. Of total vent space needed. Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier.

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. Up to 6 12 roof pitch use the standard formula as explained in this article. 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 air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials.