CSLB C-36 Plumbing ContractorRough-in PlumbingMedium
A plumbing inspector is reviewing the rough-in for a new residential DWV system. The inspector observes a horizontal wet vent serving a lavatory and a shower. The wet vent pipe diameter is 2 inches. What is the maximum developed length permitted for this 2-inch horizontal wet vent?
- A10 feet
- B6 feet
- C8 feet
- D4 feet
Show answer & explanationAnswer & explanation
Correct answer: B. 6 feet
According to the California Plumbing Code (CPC), a 2-inch horizontal wet vent serving a lavatory and a shower has a maximum developed length of 6 feet. The developed length limitation for wet vents depends on the pipe size and the fixtures served.
Why the other options are wrong
- A. This length is generally too long for a 2-inch horizontal wet vent.
- C. This length is generally too long for a 2-inch horizontal wet vent.
- D. This is typically the maximum developed length for a 1 1/2-inch horizontal wet vent.
Horizontal Wet Vent Length
The maximum developed length allowed for a horizontal pipe that serves as both a drain and a vent.
- Prevents trap seal loss due to siphoning or backpressure.
- Length limits depend on pipe size and connected fixture units.
- Critical for proper DWV system function.
Memory trick: Wet vents are dual-purpose, so don't stretch their limits too far.