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Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD

Section 501

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.

501.1 Scope. The provisions of this chapter shall control the

alteration, addition and change of occupancy of existing buildings and structures, [BSC] including state-regulated structures in accordance with Section 501.1.2. Historic build- ings and structures shall comply with Part 8, Title 24, C.C.R.

Exceptions:

1. [HCD 2] For relocated or moved buildings and maintenance, alteration, repair, addition or change of occupancy to existing buildings and accessory structures in mobilehome parks or special occu- pancy parks as provided in Section 1.8.2.1.3. See California Code of Regulations, Title 25, Division 1, Chapters 2 and 2.2. 2. [HCD 1] Limited-density owner-built rural dwell- ings.

[HCD 1] In addition to the requirements in this chapter, maintenance, alteration, repair, addition or change of occu- pancy to existing buildings and accessory structures under the authority of the Department of Housing and Community Development, as provided in Section 1.8.2.1.1, shall comply with California Code of Regulations, Title 25, Division 1, Chapter 1, Subchapter 1.

501.1.1 Compliance with other methods. Alterations, additions and changes of occupancy to existing buildings and structures shall comply with the provisions of this chapter or with one of the methods provided in Section 301.3.

501.1.2 Existing state-owned structures. [BSC] The pro- visions of Sections 317 through 322 establish minimum standards for earthquake evaluation and design for retro- fit of existing state-owned structures, including buildings owned by the University of California, the California State University and the Judicial Council. The provisions of Sections 317 through 322 may be adopted by a local jurisdiction for earthquake evaluation and design for retrofit of existing buildings.

501.2 Fire-resistance ratings. Where approved by the code

official, in buildings where an automatic sprinkler system installed in accordance with Section 903.3.1.1 or 903.3.1.2 of the California Building Code has been added, and the building is now sprinklered throughout, the required fire-resistance

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existing element that will form part of the lateral load path for any part of the addition shall be considered to be an existing lateral load-carrying structural element subject to the requirements of Section 502.5.

Exception: Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the existing building and the addition together comply with the conventional lightframe construction methods of the California Building Code or the provisions of the California Residential Code .

[BS] 502.5 Existing structural elements carrying lateral load. Where the addition is structurally independent of the existing structure, existing lateral load-carrying structural elements shall be permitted to remain unaltered. Where the addition is not structurally independent of the existing structure, the existing structure and its addition acting together as a single structure shall be shown to meet the requirements of Sections 1609 and 1613 of the California Building Code using full seismic forces.

Exceptions:

  1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the addition considered is not more than 10 percent greater than its demand-capacity ratio with the addition ignored shall be permitted to remain unaltered. For purposes of calculating demand-capacity ratios, the demand shall consider applicable load combinations with design lateral loads or forces in accordance with Sections 1609 and 1613 of the California Building Code . For purposes of this exception, comparisons of demand-capacity ratios and calculation of design lateral loads, forces and capacities shall account for the cumulative effects of additions and alterations since original construction.
  2. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the existing building and the addition together comply with the conventional light-frame construction methods of the California Building Code or the provisions of the California Residential Code .

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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
  8. Chapter 4 — REPAIRS
  9. ▸Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
    Overview
    1. Section 501
    2. Section 503
    3. Section 502
    4. Section 504
    5. Section 505
    6. Section 506
    7. Section 507
    8. Section 501A
    9. Section 502A
    10. Section 503A
    11. Section 504A
    12. Section 505A
    13. Section 506A
    14. Section 507A
  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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