NRCA’s Recommendations for Attic Ventilation
- Ventilate Attics @ 1/150 Ratio. “When designing for attic ventilation, NRCA recommends designers provide for attic ventilation in the minimum amount of 1 square foot of net free ventilation area for every 150 square feet of attic space (1:150 ventilation ratio) measured at the attic floor level (e.g. ceiling).
- Balance the Ventilation with Intake & Exhaust. “NRCA also recommends the amount of ventilation in static ventilation systems be balanced between the eave and ridge.”
- Increase the Ventilation for Steeper Roofs. “For large-volume attic spaces, such as where roof slopes are greater than 8:12, designers should consider increasing the amount of ventilation to account for additional volume of attic space.”
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