CA Plumbing PrepC-36 License Exam Prep
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Trade Exam · Module 4

Fixture Installation: The Code Rules Every Fixture Shares

Lesson 1 of 9~20 minFree previewCurrent as of September 2026Leer en español

The rules that apply to every fixture you set under the 2025 California Plumbing Code: watertight joints at walls and floors, corrosion-resistant fasteners, carriers for wall-hung fixtures, the 15, 30 and 24 inch water closet clearances, a closet flange that sits on top of the finished floor, a control valve ahead of every slip-joint supply, hot water on the left, and the trap and waste sizes that tie each fixture into the drainage system.

Key Takeaways

  • CPC 402.8 and 402.9: install every fixture per the manufacturer's installation instructions. Those instructions are part of the code requirement.
  • CPC 402.2 and 402.3: joints where a fixture meets a wall or floor must be watertight, and floor-mounted fixtures are secured with copper, copper alloy or other equally corrosion-resistant screws or bolts.
  • CPC 402.5: a water closet or bidet needs at least 15 inches from its center to a side wall or obstruction, 30 inches center to center, and 24 inches of clear space in front.
  • CPC 402.6: the bottom of the closet flange is set on top of the finished floor.
  • CPC 402.10: concealed slip joints need an access panel or utility space at least 12 inches in its least dimension.
  • CPC 606.5 and 606.6: a control valve goes immediately ahead of each slip joint or appliance supply, and it must be accessible.
  • CPC 417.5: with two handles, the left-hand control is hot when you face the fitting.
  • CPC 1001.2 and 1005.1: one trap per fixture, tailpiece no longer than 24 inches, trap seal between 2 and 4 inches.

Why This Matters

Finish Plumbing Installations is 20 percent of the C-36 trade exam in CSLB's study guide. Most of that section is about setting fixtures: water closets, lavatories, sinks, tubs and showers. Each fixture has its own section in Chapter 4 of the California Plumbing Code (CPC), but a short list of rules applies to all of them. Learn that shared list first, and the fixture-specific lessons that follow will be easier to hold in your head.

One idea runs through the whole chapter: CPC 402.8 and 402.9 say fixtures shall be installed in accordance with the manufacturer's installation instructions. On the job and on the exam, "follow the manufacturer's instructions" is not a dodge. It is the code requirement for anything the code itself does not spell out.

General Installation Rules (CPC 402)

These apply to every fixture you set:

  • Access and cleaning (402.1): fixtures are installed so they can be reached for repairs and cleaning, and pipes from fixtures run to the nearest wall.
  • Watertight joints (402.2): where a fixture touches a wall or floor, that joint is made watertight. This is the code reason you seal the joint at a fixture base or where a lavatory meets the wall.
  • Securing floor fixtures (402.3): floor-outlet and floor-mounted fixtures are rigidly secured to the drainage connection and to the floor, where designed that way, with screws or bolts of copper, copper alloy, or another equally corrosion-resistant material.
  • Wall-hung fixtures (402.4): rigidly supported by metal supporting members so no strain is transmitted to the piping connections. Floor-affixed supports for off-the-floor fixtures for public use comply with ASME A112.6.1M, and framing-affixed supports for off-the-floor water closets with concealed tanks comply with ASME A112.6.2. Flush tanks are secured with approved non-corrosive screws or bolts.
  • Setting (402.5): fixtures are set level and in proper alignment with the adjacent walls.
  • Supply fittings (402.7): supply lines and fittings are installed to prevent backflow as required by Chapter 6.
  • Slip joints (402.10): fixtures with concealed slip joint connections need an access panel or utility space not less than 12

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