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Chapter 8 — ALTERATIONS—LEVEL 2

Section 805 — STRUCTURAL

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.

[BS] 805.1 General. Structural elements and systems within buildings undergoing Level 2 alterations shall comply with this section.

[BS] 805.2 Existing structural elements carrying gravity loads. Any existing gravity load-carrying structural element for which an alteration causes an increase in design dead, live or snow load, including snow drift effects, of more than 5 percent shall be replaced or altered as needed to carry the gravity loads required by the California Building Code for new structures. Any existing gravity loadcarrying structural element whose gravity load-carrying capacity is decreased as part of the alteration shall be shown to have the capacity to resist the applicable design dead, live and snow loads, including snow drift effects, required by the California Building Code for new structures.

Exceptions:

  1. Buildings of Group R occupancy with not more than five dwelling or sleeping units used solely for residential purposes where the altered building complies with the conventional light-frame construction methods of the California Building Code or the provisions of the California Residential Code .
  2. Buildings in which the increased dead load is attributable to the addition of a second layer of roof covering weighing 3 pounds per square foot (0.1437 kN/m [2] ) or less over an existing single layer of roof covering.

[BS] 805.3 Existing structural elements resisting lateral loads. Except as permitted by Section 805.4, where the alteration increases design lateral loads, or where the alteration results in prohibited structural irregularity as defined in ASCE 7, or where the alteration decreases the capacity of any existing lateral load-carrying structural element, the lateral force-resisting system of the altered building or structure shall meet the requirements of Section 1609 of the California Building Code and Section 304.3.2 of this code.

Exceptions:

  1. Any existing lateral load-carrying structural element whose demand-capacity ratio with the alteration considered is not more than 10 percent greater than its demand-capacity ratio with the alteration 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 Section 1609 of the California Building Code and Section 304.3.1 or 304.3.2 of this code . The same methodology shall be used for the altered and unaltered structures. 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. When calculating demandcapacity ratios for wind, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 1609 of the California Building Code or the code wind forces in effect at the time. When calculating demand-capacity ratios for earthquake, the date of original construction shall be permitted to be taken as the date of completion of a prior addition, alteration or repair in compliance with Section 304.3.1 or 304.3.2 Item 1 or 3 or the full or reduced seismic forces in effect at the time.

  2. Buildings in which the increase in the demand-capacity ratio is due entirely to the addition of rooftop-supported mechanical equipment individually having an operating weight less than 400 pounds (181.4 kg) and where the total additional weight of all rooftop equipment placed after initial construction of the building is less than 10 percent of the roof dead load. For purposes of this exception, “roof” shall mean the roof level above a particular story.

  3. Increases in the demand-capacity ratio due to lateral loads from seismic forces need not be evaluated for the installation of rooftop photovoltaic panel systems where the additional roof dead load due to the system, including ballast where applicable, does not exceed 5 pounds per square foot (psf) (0.2394 kN/m [2] ) and does not exceed 10 percent of the dead load of the existing roof.

[BS] 805.4 Voluntary lateral force-resisting system alterations. Structural alterations that are intended exclusively to improve the lateral force-resisting system and are not required by other sections of this code shall not be subject to the structural requirements of this chapter or Chapter 7, provided that the following conditions are met:

  1. With the alteration complete, the capacity of existing structural systems to resist forces is not reduced.
  2. New structural elements are detailed and connected to existing or new structural elements as required by the selected design criteria. Exception: New lateral force-resisting systems designed in accordance with the California Building Code are permitted to be of a type designated as “Ordinary” or “Intermediate” where ASCE 7 Table 12.2-1 states these types of systems are not permitted.

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

ALTERATIONS—LEVEL 2

  1. Supports and attachments for nonstructural elements removed and reinstalled to facilitate the work comply with the Cali- fornia Building Code for new construction.
  2. The alterations do not create a structural irregularity as defined in ASCE 7 or make an existing structural irregularity more

severe.

Exception: Condition 4 need not be satisfied where the work complies with Section 304.3.2 Item 3.

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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
  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
    Overview
    1. Section 801 — GENERAL
    2. Section 802 — BUILDING ELEMENTS AND MATERIALS
    3. Section 803 — FIRE PROTECTION
    4. Section 804 — MEANS OF EGRESS
    5. Section 805 — STRUCTURAL
    6. Section 806 — ELECTRICAL
    7. Section 807 — MECHANICAL
    8. Section 808 — RESERVED
    9. Section 809 — ENERGY CONSERVATION
  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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