Attic Ventilation Calculator — NFVA and Vent Counts

Live calculator

Enter your measurements

Vented attic floor area

sq ft

Measure each separately vented attic or enclosed rafter space independently.Approved ratio denominator

1:n

Enter the n in the ratio approved for this assembly; no ratio is selected automatically.Approved intake share

The exhaust share is the remaining percentage.NFA per intake vent unit

in²

Use the selected intake product’s labeled net-free area per piece or linear foot.NFA per exhaust vent unit

in²

Use the selected exhaust product’s labeled net-free area per piece or linear foot.

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