Roof Ventilation Calculator
Attic Size
Enter Attic Dimensions: X feet
Calculated: square feet
or Attic Square feet: direct entry
Total NFA required: square inches
Exhaust NFA: square inches
Intake NFA: square inches
Ridge Vent: lineal feet1
Calculations are based on HUD/FHA guidelines of 1/150 ventilation to attic space ratio.
1 Based on rated NFA of 18 square inches per lineal foot.
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Call (855) 544-7767
This calculator is designed to provide estimated air intake and exhaust information based on an attic's space square footage.  Your home's architectural design and construction will impact methods used to accomplish the required Net Free Air (NFA) requirements.  All calculations are based on the 1/150 ratio as prescribed by HUD and FHA.    For a additional information contact Ready Pros, Inc. at (855)-544-7767
Attic dimensions may be entered as length and width or as the total square footage.
Results are expressed in Net Free Air (NFA) in square inches for the total home, exhaust vents only and intake vents only.
Questons? Call (855) 544-7767 for further assistance.