Drainage, Waste & VentQuestion 103 of 360
The required size of a vent pipe:
a.May be reduced by half above the roof
b.May be reduced one size above the highest fixture
c.Shall not be reduced along its length
d.May be reduced below the flood-level rim
Explanation
A vent must not be decreased in size along its required length; reducing it would restrict airflow and could cause frost or debris closure. It may be increased but not reduced. Reducing it above the roof, above the top fixture, or below the flood rim all violate this rule.
Law Reference: 2022 California Plumbing Code (CPC) §904.0Practice all 360 questions free — no signup required.
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