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Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS

Section 303

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

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

STRUCTURAL DESIGN LOADS AND EVALUATION AND DESIGN PROCEDURES

[BS] 303.1 Live loads. Where an addition or alteration does not result in increased design live load, existing gravity load-carrying structural elements shall be permitted to be evaluated and designed for live loads approved prior to the addition or alteration. If the approved live load is less than that required by Section 1607 of the California Building Code, the area designated for the nonconforming live load shall be posted with placards of approved design indicating the approved live load. Where the addition or alteration results in increased design live load, the live load required by Section 1607 of the California Building Code shall be used.

[BS] 303.2 Snow loads on adjacent buildings. Where an alteration or addition changes the potential snow drift effects on an adjacent building, the code official is authorized to enforce Section 7.12 of ASCE 7.

[BS] 303.3 Seismic evaluation and design procedures. Where required, seismic evaluation or design shall be based on the procedures and criteria in this section, regardless of which compliance method is used.

[BS] 303.3.1 Compliance with full seismic forces. Where compliance requires the use of full seismic forces, the criteria shall be in accordance with one of the following:

  1. One-hundred percent of the values in the California Building Code . Where the existing seismic forceresisting system is a type that can be designated as “Ordinary,” values of R, 0 and Cd used for analysis in accordance with Chapter 16 of the California Building Code shall be those specified for structural systems classified as “Ordinary” in accordance with

PROVISIONS FOR ALL COMPLIANCE METHODS

Table 12.2-1 of ASCE 7, unless it can be demonstrated that the structural system will provide performance equivalent to that of a “Detailed,” “Intermediate” or “Special” system. 2. ASCE 41, using a Tier 3 procedure and the twolevel performance objective in Table 303.3.1 for the applicable risk category.

[BS] 303.3.2 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, 0 and Cd used for analysis shall be as specified in Section 303.3.1 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.

[BS] TABLE 303.3.1 PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH FULL SEISMIC FORCES

RISK CATEGORY
(Based on CBC 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] TABLE 303.3.2 PERFORMANCE OBJECTIVES FOR USE IN ASCE 41 FOR COMPLIANCE WITH REDUCED SEISMIC FORCES

RISK CATEGORY
(Based on CBC 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.

Copyright © 2019 ICC. ALL RIGHTS RESERVED. Accessed by Kevin Day (kevin.day@dgs.ca.gov), (California Building Standards Commission) Order Number #100735044 on Jul 24, 2019 03:54 PM (PDT) pursuant to License Agreement with ICC. No further reproduction or distribution authorized. Single user only, copying and networking prohibited. 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.

100735044

PROVISIONS FOR ALL COMPLIANCE METHODS

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.

  1. ASCE 41, using the performance objective in Table 303.3.2 for the applicable risk category.

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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
  5. Chapter 1 — SCOPE AND ADMINISTRATION
  6. ▸Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
    Overview
    1. Section 301
    2. Section 302
    3. Section 303
    4. Section 304
    5. Section 305
    6. Section 306
    7. Section 307 — [OSHPD 1R, 2, and 5]
    8. Section 308 — [OSHPD 1R, 2 and 5]
    9. Section 309 — [OSHPD 1R]
    10. Section 313
    11. Section 314
    12. Section 315
    13. Section 316
    14. Section 317
    15. Section 318
    16. Section 319
    17. Section 320
    18. Section 321
    19. Section 322
    20. Section 323
    21. Section 302A
    22. Section 301A
    23. Section 303A
    24. Section 304A
    25. Section 305A
    26. Section 306A
    27. Section 307A
    28. Section 308A
    29. Section 309A
    30. Section 310A
  7. Chapter 4 — REPAIRS
  8. Chapter 5 — 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

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