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Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS

Section 303 — STORM SHELTERS

2025 California Existing Building Code (Title 24, Part 10) · 2025 edition · updated 2026-07-29 · California

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

303.1 General.

This section applies to the design and construction of storm shelters for the purpose of providing protection during tornadoes, hurricanes and other severe windstorms.

3-4 2025 CALIFORNIA EXISTING BUILDING CODE

on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.

PROVISIONS FOR ALL COMPLIANCE METHODS

303.1.1 Construction. Storm shelters shall be constructed in accordance with Section 423 of the California Building Code and ICC 500 and shall be designated as hurricane shelters, tornado shelters or combined hurricane and tornado shelters.

Exception: Storm shelters added to critical emergency operations facilities or Group E occupancies are not required to comply with the travel distance in Section 423.4.2 or 423.5.2 of the California Building Code .

303.2 Addition to a Group E occupancy.

Where an addition is added to an existing Group E occupancy located in an area where the shelter design wind speed for tornadoes is 250 mph (402.3 km/h) in accordance with Figure 304.2(1) of ICC 500 and the occupant load in the addition is 50 or more, the addition shall have a storm shelter constructed in accordance with ICC 500.

Exceptions:

  1. Group E day care facilities.
  2. Group E occupancies accessory to places of religious worship.
  3. Additions meeting the requirements for shelter design in ICC 500.

303.2.1 Design occupant capacity. The required design occupant capacity of the storm shelter shall include all buildings on the site, and shall be the total occupant load of the classrooms, vocational rooms and offices in the Group E occupancy.

Exceptions:

  1. Where an addition is being added on an existing Group E site, and where the addition is not of sufficient size to accommodate the required occupant capacity of the storm shelter for all of the buildings on-site, the storm shelter shall at a minimum accommodate the required capacity for the addition.
  2. Where approved by the code official, the required design occupant capacity of the shelter shall be permitted to be reduced by the design occupant capacity of any existing storm shelters on the site.

303.3 Occupancy classification.

The occupancy classification for storm shelters shall be determined in accordance with Section 423.3 of the California Building Code .

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▸ Contents — 2025 California Existing Building Code (Title 24, Part 10)
2025 California Existing Building Code (Title 24, Part 10)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. ▸ Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
    Overview
    1. Section 301 — ADMINISTRATION
    2. Section 302 — GENERAL PROVISIONS
    3. Section 303 — STORM SHELTERS
    4. Section 304 — STRUCTURAL DESIGN LOADS AND EVALUATION AND DESIG…
    5. Section 305 — IN-SITU LOAD TESTS
    6. Section 306 — ACCESSIBILITY FOR EXISTING BUILDINGS
    7. Section 307 — SMOKE ALARMS
    8. Section 308 — CARBON MONOXIDE DETECTION
    9. Section 309 — ADDITIONS AND REPLACEMENTS OF EXTERIOR WALL COVE…
    10. Section 310 — [OSHPD 1R, 2 AND 5]—SERVICES/SYSTEMS AND UTILITIES
    11. Section 311 — [OSHPD 1R, 2 AND 5]—MEANS OF EGRESS
    12. Section 312 — [OSHPD 1R]—HOSPITAL SPC AND FREESTANDING BUILDIN…
    13. Section 313 — [SFM]—EXISTING GROUP R-1 AND GROUP R-2 OCCUPANCIES
    14. Section 314 — [SFM]—EXISTING HIGH-RISE BUILDINGS
    15. Section 315 — [SFM]—EXISTING GROUP I OCCUPANCIES
    16. Section 316 — [SFM]—EXISTING GROUP L OCCUPANCIES
    17. Section 317 — [BSC, DSA-SS & DSA-SS/CC]—EARTHQUAKE EVALUATION …
    18. Section 318 — [BSC, DSA-SS & DSA-SS/CC]—DEFINITIONS
    19. Section 319 — [BSC, DSA-SS & DSA-SS/CC]—SEISMIC CRITERIA SELEC…
    20. Section 320 — [BSC, DSA-SS & DSA-SS/CC]—METHOD A
    21. Section 321 — [BSC, DSA-SS & DSA-SS/CC]—METHOD B
    22. Section 322 — [BSC, DSA-SS & DSA-SS/CC]—PEER REVIEW REQUIREMENTS
    23. Section 323 — [DSA-SS, DSA-SS/CC]—ADDITIONAL REQUIREMENTS FOR …
  4. Chapter 3A — PROVISIONS FOR ALL COMPLIANCE METHODS
  5. Chapter 4 — REPAIRS
  6. Chapter 4A — REPAIRS
  7. Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
  8. Chapter 5A — PRESCRIPTIVE COMPLIANCE METHOD
  9. Chapter 6 — CLASSIFICATION OF WORK
  10. Chapter 7 — ALTERATIONS—LEVEL 1
  11. Chapter 8 — ALTERATIONS—LEVEL 2
  12. Chapter 9 — ALTERATIONS—LEVEL 3
  13. Chapter 10 — CHANGE OF OCCUPANCY
  14. Chapter 11 — ADDITIONS
  15. Chapter 12 — HISTORIC BUILDINGS
  16. Chapter 13 — PERFORMANCE COMPLIANCE METHODS
  17. Chapter 14 — RELOCATED OR MOVED BUILDINGS
  18. Chapter 15 — CONSTRUCTION SAFEGUARDS
  19. Chapter 16 — REFERENCED STANDARDS
  20. Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING B…
  21. Appendix B — SUPPLEMENTARY ACCESSIBILITY REQUIREMENTS FOR EXIS…
  22. Appendix C — GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUIL…
  23. Appendix D — BOARD OF APPEALS
  24. Appendix E — TEMPORARY EMERGENCY USES
  25. Appendix A — GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS A…

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