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Chapter 9 — VENTS

909.1 General. Traps for island sinks and similar equipment

California Plumbing Code (Title 24, Part 5) · 2022 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

shall be roughed in above the floor and shall be permitted to be vented by extending the vent as high as possible, but not less than the drainboard height and then returning it downward and connecting it to the horizontal sink drain immediately downstream from the vertical fixture drain. The return vent shall be connected to the horizontal drain through a wyebranch fitting and shall, in addition, be provided with a foot vent taken off the vertical fixture vent by means of a wye branch immediately below the floor and extending to the nearest partition and then through the roof to the open air, or shall be permitted to be connected to other vents at a point not less than 6 inches (152 mm) above the flood-level rim of the fixtures served. Drainage fittings shall be used on the vent below the floor level, and a slope of not less than 1 ⁄ 4 inch per foot (20.8 mm/m) back to the drain shall be maintained. The return bend used under the drainboard shall be a one-piece

VENTS

fitting or an assembly of a 45 degree (0.79 rad), a 90 degree (1.57 rad), and a 45 degree (0.79 rad) elbow in the order named. Pipe sizing shall be as elsewhere required in this code. The island sink drain, upstream of the returned vent, shall serve no other fixtures. An accessible cleanout shall be installed in the vertical portion of the foot vent.

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▸Contents — California Plumbing Code (Title 24, Part 5)
California Plumbing Code (Title 24, Part 5)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. Chapter 5 — WATER HEATERS
  6. Chapter 6 — WATER SUPPLY AND DISTRIBUTION
  7. Chapter 7 — SANITARY DRAINAGE
  8. Chapter 8 — INDIRECT WASTES
  9. ▸Chapter 9 — VENTS
    Overview
    1. 901.1 Applicability. This chapter shall govern the materials,
    2. 901.2 Vents Required. Each plumbing fixture trap, except
    3. 901.3 Trap Seal Protection. The vent system shall be
    4. 902.1 Interceptor. Vent piping shall be permitted to be
    5. 902.2 Bars, Soda Fountains, and Counter. Traps serving sinks t…
    6. 903.1 Applicable Standards. Vent pipe and fittings shall
    7. 903.2 Use of Copper or Copper Alloy Tubing. Copper
    8. 903.3 Changes in Direction. Changes in the direction of
    9. 904.1 Size. The size of vent piping shall be determined from
    10. 904.2 Length. Not more than one-third of the total permitted l…
    11. 905.1 Grade. Vent and branch vent pipes shall be free from
    12. 905.2 Horizontal Drainage Pipe. Where vents connect to
    13. 905.3 Vent Pipe Rise. Unless prohibited by structural conditio…
    14. 905.4 Roof Termination. Vent pipes shall extend undiminished i…
    15. 905.5 Location of Opening. The vent pipe opening from
    16. 905.6 Common Vertical Pipe. Two fixtures shall be permitted to…
    17. 906.1 Roof Termination. Each vent pipe or stack shall
    18. 906.2 Clearance. Each vent shall terminate not less than
    19. 906.3 Use of Roof. Vent pipes shall be extended separately
    20. 906.4 Outdoor Installations. Vent pipes for outdoor
    21. 906.5 Joints. Joints at the roof around vent pipes shall be
    22. 906.6 Lead. (See Chapter 17) Sheet lead shall comply with
    23. 906.7 Frost or Snow Closure. Where frost or snow closure is li…
    24. 907.1 Drainage Stack. Each drainage stack that extends 10
    25. 907.2 Yoke Vent. The yoke vent connection to the vent stack
    26. 908.1 Vertical Wet Venting. Wet venting is limited to vertical…
    27. 908.2 Horizontal Wet Venting for a Bathroom Group.
    28. 909.1 General. Traps for island sinks and similar equipment
    29. 910.1 Where Permitted. Combination waste and vent systems shal…
    30. 910.2 Approval. Construction documents for each combination wa…
    31. 910.3 Vents. Each combination waste and vent system, as
    32. 910.4 Size. Each waste pipe and each trap in such a system
    33. 910.5 Vertical Waste Pipe. No vertical waste pipe shall be
    34. 910.6 Cleanouts. An accessible cleanout shall be installed
    35. 910.7 Fixtures. No water closet or urinal shall be installed
    36. 911.1 Circuit Vent Permitted. A maximum of eight flooroutlet w…
    37. 912.1 General. The design and sizing of a vent system shall
    38. 912.2 Minimum Requirements. An engineered vent system shall pr…
    39. 911.2 Circuit Vent Size and Connection. The circuit vent
    40. 911.3 Relief Vent. A 2 inch (50 mm) relief vent shall be provi…
    41. 911.4 Slope and Size of Horizontal Branch. The vented
    42. 911.5 Additional Fixtures. Fixtures, other than the circuitven…
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. Chapter 11 — STORM DRAINAGE
  12. Chapter 12 — FUEL GAS PIPING
  13. Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
  14. Chapter 14 — FIRESTOP PROTECTION
  15. Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
  16. Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
  19. Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
  20. Appendix C — ALTERNATE PLUMBING SYSTEMS
  21. Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
  22. Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
  23. Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS
  25. Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
  26. Appendix I — INSTALLATION STANDARDS
  27. Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
  28. Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
  29. Appendix L — SUSTAINABLE PRACTICES
  30. Appendix M — PEAK WATER DEMAND CALCULATOR
  31. Appendix N — IMPACT OF WATER TEMPERATURE ON THE POTENTIAL FOR …

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