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Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS

Section 303

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

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

303.1 Storm shelters.

This section applies to the construction of storm shelters constructed as rooms or spaces within existing buildings for the purpose of providing protection during storms that produce high winds, such as tornados and hurricanes. Such structures shall be designated to be hurricane shelters, tornado shelters, or combined hurricane and tornado shelters. Such structures shall be constructed in accordance with this code and ICC 500.

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 tornados 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 Required occupant capacity. The required occupant capacity of the storm shelter shall include all buildings on the site, and shall be the total occupant load

Copyright © 2022 by, or licensed to, International Code Council, Inc. (ALL RIGHTS RESERVED); licensed to California Building Standards Commission pursuant to License Agreement. No further reproductions is authorized. Any unauthorized reproduction or distribution is a violation of the federal copyright act and the license agreement, and subject to civil and criminal penalties thereunder.

PROVISIONS FOR ALL COMPLIANCE METHODS

the structural system will provide performance equivalent to that of a “Detailed,” “Intermediate” or “Special” system.

  1. ASCE 41, using a Tier 3 procedure and the twolevel performance objective in Table 304.3.1 for the applicable risk category.

[BS] TABLE 304.3.1 PERFORMANCE OBJECTIVES FOR USE IN ASCE 41

FOR COMPLIANCE WITH FULL SEISMIC FORCES

  1. ASCE 41, using the performance objective in Table 304.3.2 for the applicable risk category.

[BS] TABLE 304.3.2 PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH REDUCED SEISMIC FORCES

RISK
CATEGORY
(Based on IBC
Table 1604.5)		 STRUCTURAL
PERFORMANCE LEVEL
FOR USE WITH BSE-1N
EARTHQUAKE HAZARD
LEVEL		 STRUCTURAL
PERFORMANCE LEVEL
FOR USE WITH BSE-2N
EARTHQUAKE HAZARD
LEVEL
I Life Safety (S-3) Collapse Prevention (S-5)
II Life Safety (S-3) Collapse Prevention (S-5)
III Damage Control (S-2) Limited Safety (S-4)
IV Immediate Occupancy
(S-1)		 Life Safety (S-3)

[BS] 304.3.2 Compliance with reduced seismic forces. Where seismic evaluation and design is permitted to use reduced seismic forces, the criteria used shall be in accordance with one of the following:

  1. The California Building Code using 75 percent of the prescribed forces. Values of R, Ω0 and Cd used for analysis shall be as specified in Section 304.3.1 of this code.

  2. Structures or portions of structures that comply with the requirements of the applicable chapter in Appendix A as specified in Items 2.1 through 2.4 and subject to the limitations of the respective Appendix A chapters shall be deemed to comply with this section.

2.1. The seismic evaluation and design of unreinforced masonry bearing wall buildings in Risk Category I or II are permitted to be based on the procedures specified in Appendix Chapter A1.

2.2. Seismic evaluation and design of the wall anchorage system in reinforced concrete and reinforced masonry wall buildings with flexible diaphragms in Risk Category I or II are permitted to be based on the procedures specified in Chapter A2.

2.3. Seismic evaluation and design of cripple walls and sill plate anchorage in residential buildings of light-frame wood construction in Risk Category I or II are permitted to be based on the procedures specified in Chapter A3.

2.4. Seismic evaluation and design of soft, weak or open-front wall conditions in multipleunit residential buildings of wood construction in Risk Category I or II are permitted to be based on the procedures specified in Chapter A4.

RISK CATEGORY
(Based on IBC
Table 1604.5)		 STRUCTURAL
PERFORMANCE LEVEL
FOR USE WITH BSE-1E
EARTHQUAKE HAZARD
LEVEL		 STRUCTURAL
PERFORMANCE LEVEL
FOR USE WITH BSE-2E
EARTHQUAKE HAZARD
LEVEL
I Life Safety (S-3).
See Note a		 Collapse Prevention (S-
5)
II Life Safety (S-3).
See Note a		 Collapse Prevention (S-
5)
III Damage Control (S-2).
See Note a		 Limited Safety (S-4).
See Note b
IV Immediate Occupancy
(S-1)		 Life Safety (S-3).
See Note c

a. For Risk Categories I, II and III, the Tier 1 and Tier 2 procedures need not

be considered for the BSE-1E earthquake hazard level. b. For Risk Category III, the Tier 1 screening checklists shall be based on the

Collapse Prevention, except that checklist statements using the Quick Check provisions shall be based on MS -factors that are the average of the values for Collapse Prevention and Life Safety. c. For Risk Category IV, the Tier 1 screening checklists shall be based on

Collapse Prevention, except that checklist statements using the Quick Check provisions shall be based on MS -factors for Life Safety.

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▸Contents — California Existing Building Code (Title 24, Part 10)
California Existing Building Code (Title 24, Part 10)
  1. Chapter 2 — DEFINITIONS
  2. Appendix A — GUIDELINES FOR
  3. Appendix B — SUPPLEMENTARY
  4. Appendix C — GUIDELINES FOR THE WIND
  5. Appendix D — BOARD OF
  6. Chapter 1 — SCOPE AND ADMINISTRATION
  7. ▸Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
    Overview
    1. Section 301
    2. Section 302
    3. Section 304
    4. Section 303
    5. Section 305
    6. Section 306
    7. Section 309
    8. Section 310 — [OSHPD 1R, 2 and 5]
    9. Section 311 — [OSHPD 1R, 2 and 5]
    10. Section 307
    11. Section 308
    12. Section 312 — [OSHPD 1R]
    13. Section 313 — [SFM]
    14. Section 314 — [SFM]
    15. Section 315 — [SFM]
    16. Section 316 — [SFM]
    17. Section 317
    18. Section 319
    19. Section 318
    20. Section 320
    21. Section 321
    22. Section 322
    23. Section 323 — [DSA-SS, DSA-SS/CC]
    24. Section 301A
    25. Section 302A
    26. Section 303A
    27. Section 304A
    28. Section 305A
    29. Section 306A
    30. Section 307A — 309 A
    31. Section 310A
    32. Section 311A
    33. Section 312A
    34. Section 313A
  8. Chapter 4 — REPAIRS
  9. Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
  10. Chapter 6 — CLASSIFICATION OF WORK
  11. Chapter 7 — ALTERATIONS—LEVEL 1
  12. Chapter 8 — ALTERATIONS—LEVEL 2
  13. Chapter 9 — ALTERATIONS—LEVEL 3
  14. Chapter 10 — CHANGE OF OCCUPANCY
  15. Chapter 11 — ADDITIONS
  16. Chapter 12 — HISTORIC BUILDINGS
  17. Chapter 13 — PERFORMANCE COMPLIANCE METHODS
  18. Chapter 14 — RELOCATED OR MOVED BUILDINGS
  19. Chapter 15 — CONSTRUCTION SAFEGUARDS
  20. Chapter 16 — REFERENCED STANDARDS

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