Attic Ventilation Calculator
Calculate the proper attic ventilation requirements for optimal air flow, moisture control, and energy efficiency. Determine vent needs based on attic area, vent type, and climate conditions.
Step 1: Attic Specifications
Understanding Attic Ventilation
Proper ventilation follows the 1/300 rule: 1 sq ft of vent area per 300 sq ft of attic floor space. For moisture-prone areas, use the 1/150 rule.
Step 2: Climate & Ventilation Details
About Proper Ventilation
Adequate attic ventilation prevents moisture buildup, reduces cooling costs, and extends roof life. Intake and exhaust vents should be balanced for optimal airflow.
Ventilation Requirements
Required Net Free Vent Area (NFVA)
Vent Type Comparison
| Vent Type | Best For | NFVA Efficiency | Installation |
|---|
Ventilation Breakdown
Ventilation Calculation Formula
NFVA = (Attic Area ÷ Ratio) × Climate Factor × Moisture Factor
Standard ratio is 1:300 (1 sq ft vent per 300 sq ft attic). Humid climates or high moisture concerns use 1:150 ratio for increased ventilation.
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