Roof Venting Ratio

And this guideline you ll need a minimum of.

Roof venting ratio.

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. The ratio of soffit intake to roof outlet should be at least 2 1 to avoid unnecessary these heat losses from the building. 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.

In order to find the right calculator divide the attic floor space by 300 sq feet. A serious error is a roof outlet vent net free area that exceeds the air inlets at lower roof edges or eaves. 1 square foot of nfva per 300 square feet of attic floor if a vapor barrier is installed on the ceiling below. 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.

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