CSLB C-36 Plumbing ContractorRough-in PlumbingHard

A plumbing contractor is roughing in a new residential DWV system. A 2-inch horizontal wet vent is planned to serve a shower and a lavatory. What is the maximum developed length permitted for this 2-inch horizontal wet vent?

  1. A8 feet
  2. B15 feet
  3. C12 feet
  4. D10 feet
Show answer & explanation

Correct answer: D. 10 feet

Horizontal wet vents have specific length limitations based on their diameter to ensure adequate venting and prevent trap seal loss. For a 2-inch horizontal wet vent, the Uniform Plumbing Code (UPC) typically allows a maximum developed length of 10 feet.

Why the other options are wrong

  • A. This length is too short for a 2-inch wet vent and not a standard maximum.
  • B. This length is generally too long for a horizontal wet vent of this diameter.
  • C. This length exceeds the typical maximum for a 2-inch horizontal wet vent.

Horizontal Wet Vent Length

The maximum allowable developed length of a horizontal pipe that serves as both a drain and a vent for fixtures, limited by code to ensure effective trap seal protection.

  • Pipe acts as both drain and vent.
  • Length limits are crucial for performance.
  • Limits vary by pipe size and code.

Memory trick: Wet Vents need 'Exact Lengths' for proper breathing.

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