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Chapter 21A — MASONRY

Section 2107A — ALLOWABLE STRESS DESIGN

2025 California Building Code (Title 24, Part 2) · 2025 edition · updated 2026-07-29 · California

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

2107 A .1 General. The design of masonry structures using allowable stress design shall comply with Section 2106 and the requirements of Chapters 1 through 8 of TMS 402 except as modified by Sections 2107 A .2 through 2107A.4.

2107 A .2 TMS 402, Section 6.1.7.1, lap splices. As an alternative to Section 6.1.7.1, it shall be permitted to design lap splices in accordance with Section 2107 A .2.1.

2107 A .2.1 Lap splices. The minimum length of lap splices for reinforcing bars in tension or compression, l d, shall be:

Equation 21 A -1 l d = 0.002 d b f s

For SI: l d = 0.29 d b f s

but not less than 12 inches (305 mm). The length of the lapped splice shall be not less than 40 bar diameters.

In regions of moment where the design tensile stresses in the reinforcement are greater than 80 percent of F s, the lap length of splices shall be increased not less than 50 percent of the minimum required length, but need not be greater than 72 d b . Other equivalent means of stress transfer to accomplish the same 50 percent increase shall be permitted. Where epoxy coated bars are used, lap length shall be increased by 50 percent.

2107 A .3 TMS 402, Section 6.1.7, splices of reinforcement. Add to Section 6.1.7 as follows:

6.1.7 – Splices of reinforcement. Lap splices, welded splices or mechanical splices are permitted in accordance with the provisions of this section. Welding shall conform to AWS D1.4. Welded splices shall be of ASTM A706 steel reinforcement. Reinforcement larger than No. 9 (M #29) shall be spliced using mechanical connections in accordance with Section 6.1.7.2.

2107A.4 TMS 402, Section 8.3.4.4 Walls.

Modify TMS 402, Section 8.3.4.4 as follows by adding:

8.3.4.4.1 The minimum thickness of walls is given in this section. Stresses shall be determined on the basis of the net thickness of the masonry, with consideration for reduction, such as raked joints.

8.3.4.4.2 The thickness of masonry walls shall be designed so that allowable maximum stresses specified in this chapter are not exceeded. Masonry walls shall not exceed the height or length-to-thickness ratio nor be less than the minimum thickness as specified in this chapter and as set forth in Table 8.3.4.4.

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

MASONRY

TABLE 8.3.4.4-MINIMUM THICKNESS OF MASONRY WALLS1, 2

TYPE OF MASONRY MAXIMUM RATIO UNSUPPORTED
HEIGHT OR LENGTH TO THICKNESS2,3		 NOMINAL MINIMUM
THICKNESS (inches)
BEARING OR SHEAR WALLS:
1. Stone masonry
2. Reinforced grouted masonry
3. Reinforced hollow unit masonry		 14
25
25		 16
6
6
NONBEARING WALLS:
4. Exterior reinforced walls
5. Interior partitions reinforced		 30
36		 6
4
1. For walls of varying thickness, use the least thickness when determining the height or length to thickness ratio.
2. In determining the height or length-to-thickness ratio of a cantilevered wall, the dimension to be used shall be twice the dimension of the end of the wall from the lateral support.
3. Cantilevered walls not part of a building and not carrying applied vertical loads need not meet these minimum requirements but their design must comply with stress and over-
turning requirements.

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8.3.4.4.3 Every pier or wall section with a width less than three times its thickness shall be designed and constructed as required for columns if such pier is a structural member. Every pier or wall section with a width between three and five times its thickness or less than one half the height of adjacent openings shall have all horizontal steel in the form of ties except that in walls 12 inches (305 mm) or less in thickness such steel may be in the form of hair-pins.

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▸ Contents — 2025 California Building Code (Title 24, Part 2)
2025 California Building Code (Title 24, Part 2)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — OCCUPANCY CLASSIFICATION AND USE
  4. Chapter 4 — SPECIAL DETAILED REQUIREMENTS BASED ON OCCUPANCY A…
  5. Chapter 5 — GENERAL BUILDING HEIGHTS AND AREAS
  6. Chapter 6 — TYPES OF CONSTRUCTION
  7. Chapter 7 — FIRE AND SMOKE PROTECTION FEATURES
  8. Chapter 7A — MATERIALS AND CONSTRUCTION METHODS FOR EXTERIOR W…
  9. Chapter 8 — INTERIOR FINISHES
  10. Chapter 9 — FIRE PROTECTION AND LIFE SAFETY SYSTEMS
  11. Chapter 10 — MEANS OF EGRESS
  12. Chapter 11 — RESERVED
  13. Chapter 11A — HOUSING ACCESSIBILITY
  14. Chapter 11B — ACCESSIBILITY TO PUBLIC BUILDINGS, PUBLIC ACCOMM…
  15. Chapter 12 — INTERIOR ENVIRONMENT
  16. Chapter 13 — ENERGY EFFICIENCY
  17. Chapter 14 — EXTERIOR WALLS
  18. Chapter 15 — ROOF ASSEMBLIES AND ROOFTOP STRUCTURES
  19. Chapter 16 — STRUCTURAL DESIGN
  20. Chapter 16A — STRUCTURAL DESIGN
  21. Chapter 17 — SPECIAL INSPECTIONS AND TESTS
  22. Chapter 17A — SPECIAL INSPECTIONS AND TESTS
  23. Chapter 18 — SOILS AND FOUNDATIONS
  24. Chapter 18A — SOILS AND FOUNDATIONS
  25. Chapter 19 — CONCRETE
  26. Chapter 19A — CONCRETE
  27. Chapter 20 — ALUMINUM
  28. Chapter 21 — MASONRY
  29. ▸ Chapter 21A — MASONRY
    Overview
    1. Section 2101A — GENERAL
    2. Section 2102A — NOTATIONS
    3. Section 2103A — MASONRY CONSTRUCTION MATERIALS
    4. Section 2104A — CONSTRUCTION
    5. Section 2105A — QUALITY ASSURANCE
    6. Section 2106A — SEISMIC DESIGN
    7. Section 2107A — ALLOWABLE STRESS DESIGN
    8. Section 2108A — STRENGTH DESIGN OF MASONRY
    9. Section 2109A — EMPIRICAL DESIGN OF ADOBE MASONRY
    10. Section 2110A — GLASS UNIT MASONRY
    11. Section 2111A — MASONRY FIREPLACES
    12. Section 2112A — MASONRY HEATERS
    13. Section 2113A — MASONRY CHIMNEYS
    14. Section 2114A — DRY-STACK MASONRY
  30. Chapter 22 — STEEL
  31. Chapter 22A — STEEL
  32. Chapter 23 — WOOD
  33. Chapter 24 — GLASS AND GLAZING
  34. Chapter 25 — GYPSUM PANEL PRODUCTS AND PLASTER
  35. Chapter 26 — PLASTIC
  36. Chapter 27 — ELECTRICAL
  37. Chapter 28 — MECHANICAL SYSTEMS
  38. Chapter 29 — PLUMBING SYSTEMS
  39. Chapter 30 — ELEVATORS AND CONVEYING SYSTEMS
  40. Chapter 31 — SPECIAL CONSTRUCTION
  41. Chapter 31A — SYSTEMS FOR WINDOW CLEANING OR EXTERIOR BUILDING…
  42. Chapter 31B — PUBLIC POOLS
  43. Chapter 31C — RADIATION
  44. Chapter 31D — FOOD ESTABLISHMENTS
  45. Chapter 31F — MARINE OIL TERMINALS
  46. Chapter 32 — ENCROACHMENTS INTO THE PUBLIC RIGHT-OF-WAY
  47. Chapter 33 — SAFEGUARDS DURING CONSTRUCTION
  48. Chapter 34 — RESERVED
  49. Chapter 35 — REFERENCED STANDARDS
  50. Appendix A — EMPLOYEE QUALIFICATIONS
  51. Appendix B — BOARD OF APPEALS
  52. Appendix C — GROUP U—AGRICULTURAL BUILDINGS
  53. Appendix D — FIRE DISTRICTS
  54. Appendix E — RESERVED
  55. Appendix F — RODENTPROOFING
  56. Appendix G — FLOOD-RESISTANT CONSTRUCTION
  57. Appendix H — SIGNS
  58. Appendix I — PATIO COVERS
  59. Appendix J — GRADING
  60. Appendix K — GROUP R-3 AND GROUP R-3.1 OCCUPANCIES PROTECTED B…
  61. Appendix L — EARTHQUAKE RECORDING INSTRUMENTATION
  62. Appendix M — TSUNAMI-GENERATED FLOOD HAZARDS
  63. Appendix N — REPLICABLE BUILDINGS
  64. Appendix O — PERFORMANCE-BASED APPLICATION
  65. Appendix P — SLEEPING LOFTS
  66. Appendix Q — EMERGENCY HOUSING

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