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Chapter 11 — STORM DRAINAGE

1101.8 Areaway Drains. Open subsurface space adjacent

California Plumbing Code (Title 24, Part 5) · 2019 edition · updated 2026-09-10 · California

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

to a building, serving as an entrance to the basement or cellar of a building, shall be provided with a drain or drains. The areaway drains shall be not less than 2 inches (50 mm) in diameter for areaways at a maximum of 100 square feet (9.29

212 2019 CALIFORNIA PLUMBING CODE

STORM DRAINAGE

tion 1101.12.1. The secondary roof drains shall connect to a piping system in accordance with Section 1101.12.2.2.1 or Section 1101.12.2.2.2. 1101.12.2.2.1 Separate Piping System. The secondary roof drainage system shall be a separate system of piping, independent of the primary roof drainage system. The discharge shall be above grade, in a location observable by the building occupants or maintenance personnel. Secondary roof drain systems shall be sized in accordance with Section 1101.12.1 based on the rainfall rate for which the primary system is sized. 1101.12.2.2.2 Combined System. The secondary roof drains shall connect to the vertical piping of the primary storm drainage conductor downstream of the last horizontal offset located below the roof. The primary storm drainage system shall connect to the building storm water that connects to an underground public storm sewer. The combined secondary and primary roof drain systems shall be sized in accordance with Section 1103.0 based on double the rainfall rate for the local area.

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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
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. ▸Chapter 11 — STORM DRAINAGE
    Overview
    1. 1101.2 Where Required. Roofs, paved areas, yards, courts,
    2. 1101.3 Storm Water Drainage to Sanitary Sewer Pro-hibited. Sto…
    3. 1101.4 Material Uses. Pipe, tube, and fittings conveying
    4. 1101.5 Expansion Joints Required. Expansion joints or
    5. 1101.6 Subsoil Drains. Subsoil drains shall be provided
    6. 1101.9 Window Areaway Drains. Window areaways at a
    7. 1101.10 Filling Stations and Motor Vehicle WashingEstablishmen…
    8. 1101.11 Paved Areas. Where the occupant creates surface
    9. 1101.12 Roof Drainage. Roof drainage shall comply with
    10. 1101.7 Building Subdrains. Building subdrains located
    11. 1101.8 Areaway Drains. Open subsurface space adjacent
    12. 1101.13 Cleanouts. Cleanouts for building storm drains
    13. 1101.16 Leaders, Conductors, and Connections.
    14. 1101.14 Rainwater Sumps. Rainwater sumps serving
    15. 1101.15 Traps on Storm Drains and Leaders. Leaders
    16. 1102.2 Dome Strainers Required. Roof drains shall have
    17. 1102.3 Roof Drain Flashings. The connection between
    18. 1103.2 Size of Horizontal Storm Drains and Sewers.
    19. 1103.3 Size of Roof Gutters. The size of semi-circular
    20. 1103.4 Side Walls Draining onto a Roof. Where vertical walls p…
    21. 1104.0 Values for Continuous Flow.1104.1 General. Where there …
    22. 1105.0 Controlled-Flow Roof Drainage.1105.1 Application. Inste…
    23. 1105.2 Setback Roofs. Drains on setback roofs shall be
    24. 1106.2 Siphonic Roof Drainage Systems. The design of
    25. 1106.3 Siphonic Roof Drains. Siphonic roof drains shall
    26. 1107.2 Methods of Testing Storm Drainage Systems. Except for o…
  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 STANDARD FOR PEX TUBING SYSTEMS FOR …
  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

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