ATTic ventilation

Attic Ventilation Calculator

Required Net Free Area by code, the low/high split, and how many of our go-to GAF & Attic Breeze vents that means.

sq ft
0 sq in
Total NFA Required
Low/Intake 0 sq in High/Exhaust 0 sq in
0 CFMrequired

Sized off the High/Exhaust NFA above, rounded up to full pieces.

Cobra Hip Vent Cobra® Hip Vent
Cobra® Hip Vent
9 sq in/ft · 4 ft sticks · hip roofs
0 sticks
0 sq in NFA
Master Flow SSB960 Master Flow™ SSB960
Master Flow™ SSB960
60 sq in NFA/unit · roof louver
0 vents
0 sq in NFA
Master Flow Dome Vent Master Flow™ Dome Vent
Master Flow™ Dome Vent
144 sq in NFA/unit · low profile
0 vents
0 sq in NFA

Sized off GAF's own turbine chart (by attic sq ft, not NFA math).

Sized by airflow (CFM) — see the options above.

Same required airflow as the electric option.

ⓘ These are exhaust options. Pair with enough soffit/eave intake to cover the Low/Intake number above.
Sources & assumptions
Sources & assumptions: The Total/Low/High NFA figures follow the general IRC R806.2 rule (1⁄150 minimum, reducible to 1⁄300 with roughly balanced high/low venting), split 50/50 between intake and exhaust. Cobra® Hip Vent (9 sq in NFA/lin ft, 4 ft sticks), Master Flow™ SSB960 (60 sq in NFA/unit), and Master Flow™ High-Capacity Dome Vent (144 sq in NFA/unit) figures are from current GAF data sheets. Master Flow™ Aluminum Wind Turbine quantities follow GAF's own published sizing chart for 12" and 14" turbines (extrapolated using the chart's own trend for attics over 3,000 sq ft, since GAF's chart stops there). Master Flow™ Power Attic Vent (ERV6HT roof mount/1,500 CFM, EGV5 gable mount/1,450 CFM) and Attic Breeze UltraBreeze™ (PRO/1,550 CFM, HP/1,775 CFM, MAX/1,925 CFM) figures are manufacturer free-air CFM ratings. Fan CFM sizing uses the common rule of thumb of 0.7 CFM per sq ft of attic floor. Product photos are hotlinked from GAF's and RoofingDirect's product image hosting and may change; a text label appears in their place if an image ever fails to load. Real installs vary by roof shape, obstructions, attic configuration, and local code — confirm exact products, quantities, and whether a powered fan is permitted in place of (or in addition to) passive venting with a roofing professional, current GAF/Attic Breeze spec sheets, and your local building department before ordering materials.