Core TradesQuestion 204 of 700
For an enclosed attic without a vapor retarder or balanced venting, the net free ventilating area must generally be at least what fraction of the vented attic floor area?
a.1/50
b.1/150
c.1/300
d.1/600
Explanation
The baseline requirement is a net free vent area of at least 1/150 of the attic floor area. The 1/300 ratio is allowed only when specific conditions such as a vapor retarder or balanced high-and-low venting are met; 1/50 and 1/600 are not the standard code fractions.
Law Reference: 2025 CA Residential Code, R806 (Roof Ventilation)Practice all 700 questions free — no signup required.
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