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Codes & Ratings

What is Ventilation Code?

Roofing Glossary · Codes & Ratings

Definition

The building code requirements specifying minimum attic ventilation ratios to prevent moisture accumulation and heat buildup. The IRC requires a minimum net free ventilation area of 1/150 of the attic floor area, reducible to 1/300 when at least 40% (and not more than 50%) of the ventilation is in the upper portion of the space (i.e., ridge venting). Proper code-compliant ventilation is a condition of most shingle warranties.

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