Drainage, Waste & VentQuestion 156 of 360
When a primary roof drain could become blocked and allow water to pond on the roof, the code requires…
a.a larger sanitary vent
b.a backwater valve on the roof drain
c.no additional provision
d.a secondary (overflow) roof drainage system or scuppers with independent discharge
Explanation
Roofs must have a secondary (overflow) drainage system, such as overflow drains or scuppers, in case the primary roof drains clog. The overflow discharges independently so that a blockage does not let water accumulate to a structurally dangerous depth. This protects the roof structure from collapse under ponding loads.
Law Reference: 2022 California Plumbing Code (CPC) §1101.0Practice all 360 questions free — no signup required.
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