Roof Ventilation Calculator
Calculate the proper ventilation requirements for your roof. Determine intake and exhaust ventilation needs based on attic area and roof type for optimal airflow.
Step 1: Attic Details
Understanding Attic Ventilation
Proper attic ventilation prevents moisture buildup, reduces cooling costs, and extends roof life. The general rule is 1 sq ft of ventilation per 300 sq ft of attic space with a vapor barrier, or 1:150 without.
Step 2: Ventilation Details
About Net Free Area (NFA)
NFA is the actual open area for air to flow through a vent after accounting for screens and louvers. Higher efficiency vents have more NFA per vent size, providing better airflow.
Ventilation Requirements
Total Ventilation Required
Ventilation Type Comparison
| Ventilation Type | Best For | NFA per Vent | Cost per Vent | Installation Difficulty |
|---|
Ventilation Analysis
Ventilation Formula
Ventilation = Attic Area ÷ Ventilation Ratio
The total net free ventilation area needed is calculated by dividing your attic floor area by the recommended ratio (typically 1:150 or 1:300 depending on climate and vapor barriers).
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