CSLB C-36 Plumbing ContractorFixture and Appliance InstallationMedium

A plumber is installing a new wall-mounted toilet. Which of the following is the most critical consideration for ensuring a secure and code-compliant installation?

  1. AThe color and style of the toilet match the bathroom decor.
  2. BThe toilet seat is soft-close for comfort.
  3. CThe rough-in dimensions match the specified carrier frame.
  4. DThe flush mechanism is dual-flush for water efficiency.
Show answer & explanation

Correct answer: C. The rough-in dimensions match the specified carrier frame.

Wall-mounted toilets rely on a concealed carrier frame for support. The rough-in dimensions of the drain and mounting bolts must precisely match the specifications of this carrier frame for a secure, stable, and code-compliant installation. Incorrect rough-in will prevent proper mounting.

Why the other options are wrong

  • A. Aesthetic considerations are not critical for structural integrity or code compliance.
  • B. Soft-close seats are comfort features, not critical for core installation.
  • D. Dual-flush mechanisms relate to water efficiency, not the physical mounting and stability of the toilet.

Wall-Mounted Toilet Rough-in

The specific measurements and positioning of the drain connection, water supply, and mounting bolts required for the installation of a wall-mounted toilet's carrier frame.

  • Crucial for structural integrity and proper function.
  • Must match the manufacturer's specifications for the carrier.
  • Incorrect rough-in leads to installation failure or instability.

Memory trick: Rough-in 'Right' ensures a 'Rigid' and 'Reliable' install.

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