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Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING BUILDINGS

Section A402 — DEFINITIONS

2025 California Existing Building Code (Title 24, Part 10) · 2025 edition · updated 2026-07-27 · California

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

[BS] A402.1 Definitions. Notwithstanding the applicable definitions, symbols and notations in the building code, the following definitions shall apply for the purposes of this chapter:

[BS] ASPECT RATIO. The span-width ratio for horizontal diaphragms and the height-length ratio for shear walls.

[BS] NONCONFORMING STRUCTURAL MATERIALS. Wall bracing materials other than wood structural panels or diagonal sheathing.

[BS] OPEN-FRONT WALL LINE. An exterior wall line, without vertical elements of the lateral force-resisting system, that requires tributary seismic forces to be resisted by diaphragm rotation or excessive cantilever beyond parallel lines of shear walls. Diaphragms that cantilever more than 25 percent of the distance between lines of lateral force-resisting elements from which the diaphragm cantilevers shall be considered to be excessive. Exterior exit balconies of 6 feet (1829 mm) or less in width shall not be considered excessive cantilevers.

[BS] RETROFIT. An improvement of the lateral force-resisting system by alteration of existing structural elements or addition of new structural elements.

[BS] SOFT WALL LINE. A wall line whose lateral stiffness is less than that required by story drift limitations or deformation compatibility requirements of this chapter. In lieu of analysis, a soft wall line may be defined as a wall line in a story where the story stiffness is less than 70 percent of the story above for the direction under consideration.

[BS] STORY. A story as defined by the building code, including any basement or underfloor space of a building with cripple walls exceeding 4 feet (1219 mm) in height.

[BS] WALL LINE. Any length of wall along a principal axis of the building used to provide resistance to lateral loads. Parallel wall lines separated by less than 4 feet (1219 mm) shall be considered to be one wall line for the distribution of loads.

[BS] WEAK WALL LINE. A wall line in a story where the story strength is less than 80 percent of the story above in the direction under consideration.

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▸ Contents — 2025 California Existing Building Code (Title 24, Part 10)
2025 California Existing Building Code (Title 24, Part 10)
  1. 104.11 for consideration of alternative means of compliance.
  2. Chapter 1 — ADMINISTRATION
  3. Chapter 2 — DEFINITIONS
  4. Chapter 3 — PROVISIONS FOR ALL COMPLIANCE METHODS
  5. Chapter 3A — PROVISIONS FOR ALL COMPLIANCE METHODS
  6. Chapter 4 — REPAIRS
  7. Chapter 4A — REPAIRS
  8. Chapter 5 — PRESCRIPTIVE COMPLIANCE METHOD
  9. Chapter 5A — 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
  21. ▸ Appendix A — GUIDELINES FOR THE SEISMIC RETROFIT OF EXISTING B…
    Overview
    1. Section A100 — APPLICATION
    2. Section A101 — PURPOSE
    3. Section A102 — SCOPE
    4. Section A103 — DEFINITIONS
    5. Section A104 — SYMBOLS AND NOTATIONS
    6. Section A105 — GENERAL REQUIREMENTS
    7. Section A106 — MATERIALS REQUIREMENTS
    8. Section A107 — QUALITY CONTROL
    9. Section A108 — DESIGN STRENGTHS
    10. Section A109 — ANALYSIS AND DESIGN PROCEDURE
    11. Section A110 — GENERAL PROCEDURE
    12. Section A111 — SPECIAL PROCEDURE
    13. Section A112 — ANALYSIS AND DESIGN
    14. Section A113 — DETAILED BUILDING SYSTEM DESIGN REQUIREMENTS
    15. Section A114 — WALLS OF UNBURNED CLAY, ADOBE OR STONE MASONRY
    16. Section A201 — PURPOSE
    17. Section A202 — SCOPE
    18. Section A203 — DEFINITIONS
    19. Section A204 — SYMBOLS AND NOTATIONS
    20. Section A205 — GENERAL REQUIREMENTS
    21. Section A206 — ANALYSIS AND DESIGN
    22. Section A207 — MATERIALS OF CONSTRUCTION
    23. Section A301 — GENERAL
    24. Section A302 — DEFINITIONS
    25. Section A303 — STRUCTURAL WEAKNESSES
    26. Section A304 — STRENGTHENING REQUIREMENTS
    27. Section A401 — GENERAL
    28. Section A402 — DEFINITIONS
    29. Section A403 — ANALYSIS AND DESIGN
    30. Section A404 — PRESCRIPTIVE MEASURES FOR WEAK STORY
    31. Section A405 — MATERIALS OF CONSTRUCTION
    32. Section A406 — CONSTRUCTION DOCUMENTS
    33. Section A407 — QUALITY CONTROL
    34. Section A501 — REFERENCED STANDARDS
  22. Appendix B — SUPPLEMENTARY ACCESSIBILITY REQUIREMENTS FOR EXIS…
  23. Appendix C — GUIDELINES FOR THE WIND RETROFIT OF EXISTING BUIL…
  24. Appendix D — BOARD OF APPEALS
  25. Appendix E — TEMPORARY EMERGENCY USES
  26. Appendix A — GUIDELINES ON FIRE RATINGS OF ARCHAIC MATERIALS A…

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