How Many Roof Vents Per Square Foot

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.

How many roof vents per square foot.

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. 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. 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.

If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. 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. Enter square footage calculate or enter the square footage of the attic or area to be vented.

What are the building code requirements for ventilating a 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. 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. 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. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. To find the squares divide the overall roof area by 100 and then round up. 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.

There should also be a 50 50 balance of attic venting and roof venting. This is simply 100 square feet of roof. 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.