Drainage, Waste & VentQuestion 104 of 360
In areas subject to frost closure, a vent extension through the roof must be increased to a minimum of 3 inches, and the change in size must be made at least:
a.3 inches below the roof
b.6 inches below the roof
c.2 feet below the roof
d.1 foot (12 inches) inside the building below the roof
Explanation
Where frost or snow closure is a concern, the vent must be at least 3 inches in diameter through the roof, and the increase in size must be made at least 1 foot inside the building below the roof. Making the transition too close to the roof line (3 or 6 inches) leaves the enlarged section exposed to frost, and 2 feet is more than the code requires.
Law Reference: 2022 California Plumbing Code (CPC) §906.7Practice all 360 questions free — no signup required.
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