27 lineal feet required.
Roof venting formula.
Of total vent space 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.
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.
Ft divided by 150 equals 10 sq.
A ridge vent is installed at the peak of the roof where the hot air rises to.
Ventsure 4 foot strip heat moisture ridge vent.
Proper air circulation through the attic space helps lower cooling bills and prolongs the life of roofing materials.
Length x width of attic in feet 150 total sq.
Calculate the total vent area needed.
The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation.
A normal metal pot vent produces only 50 squares inches of free net area.
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.
Now you know how many square inches of attic roof venting you need for the roof and soffit.
7 12 to 10 12 roof pitches increase the amount of ventilation by 20 percent.
For projects involving vents with motors the calculation formula is different.
So we would need at least six metal vents in addition to the lower soffit ventilation to meet minimum ventilation requirements.
Ventsure 4 foot strip heat moisture ridge vent with weather protector moisture barrier.
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.
How to determine the number of attic vents.
Next divide that number by 2.
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.
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.
