Roof Vents Per Square Foot

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.

Roof vents per square foot.

Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. The calculations before indicated that we needed 2 square feet of ridge or upper roof ventilation. And this guideline you ll need a minimum of. Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space.

So the ridge ventilation has exceeded the minimum requirement. 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. 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. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space.

This formula is traditionally used for static roof vents which are rated for net free area in terms of square inches. Nine hundred square inches equals 6 25 square feet. Use this calculator to help determine the proper amount of attic ventilation based on u s. Near ridge of the roof.

Based on your 1100 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. Standard ridge vent produces 18 square inches of ventilating area per lineal 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.

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. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space. Building codes typically echo the administration s guidelines.