Roof Vent 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 vent per square foot.

This formula is traditionally used for static roof vents which are rated for net free area in terms of square inches. As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. The federal housing administration recommends 1 square foot of attic ventilation for every 150 square feet of attic space. 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.

Our roof is 50 feet long so using a standard product we will get 900 square inches of ventilating space. 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. If there is no vapor barrier double it to one square foot of nfa for every 150 square feet of attic floor space half for intake half for exhaust. 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.

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 attic floor has a vapor barrier you will need one square foot of nfa per every 300 square feet of attic floor area half of that will be intake half for exhaust. Based on your 1100 sq. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet.

And this guideline you ll need a minimum of. 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. 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. So the ridge ventilation has exceeded the minimum requirement.

Standard ridge vent produces 18 square inches of ventilating area per lineal foot. Nine hundred square inches equals 6 25 square feet. Building codes typically echo the administration s guidelines.