How Many Roof Vents Per Square Foot

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 many roof vents per square foot.

This is simply 100 square feet of roof. According to their requirements you should have 1 square foot of attic ventilation per 300 sq ft of attic floor space. 6 measure the radius of round vents or take half the diameter of the. A square simply refers to a 10 x 10 square of roofing.

To find the squares divide the overall roof area by 100 and then round up. If your roof is 1200 sq ft soffit floor space you will need 4 sq feet of roof ventilation. 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. 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.

Enter square footage calculate or enter the square footage of the attic or area to be vented. This formula is traditionally used for static roof vents which are rated for net free area in terms of 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. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

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. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. 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. 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.

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. There should also be a 50 50 balance of attic venting and roof venting. 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.