How Many Roof Vents Per Square Foot

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator.

How many roof vents per square foot.

This means that for every 300 square feet of enclosed attic space 1 square foot of ventilation is required with half at the upper portion exhaust vents and half in the lower portion intake 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. 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. To find the squares divide the overall roof area by 100 and then round up.

This is simply 100 square feet of roof. 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. 6 measure the radius of round vents or take half the diameter of the. There should also be a 50 50 balance of attic venting and roof venting.

They should be divided equally between inlet and outlet vents and they can be used in any combination that will work with your roof s design. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. A square simply refers to a 10 x 10 square of roofing.

This shortcut conveniently calculates the 2015 international residential building code minimum irc section r806 roof ventilation 1 which states in part 1 square foot of net free area for every 150 square feet of attic floor space with the attic defined as length x width floor of the attic. For example a 6 by 12 inch soffit vent has 72 square inches which when divided by 144 results in a 0 5 square foot opening. 1 square foot of ventilation for every 300 square feet of space for pitched roofs with vapor barriers 1 square foot of ventilation for every 150 square feet of space no vapor barrier and for some municipalities in hot climates. This formula is traditionally used for static roof vents which are rated for net free area in terms of square inches.

Roofing contractors estimate projects and materials by the square so it is crucial to find this measurement to accurately estimate the amount of material needed. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. What are the building code requirements for ventilating a roof.