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Appendix BJ — STRAWBALE CONSTRUCTION

Section BJ103 — BALES

2025 California Residential Code (Title 24, Part 2.5) · 2025 edition · updated 2026-07-27 · California

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

BJ103.1 Shape.

Bales shall be rectangular in shape, except for partial bales made to fill nonrectangular spaces in accordance with Section BJ103.6.

BJ103.2 Size.

Bales shall have a height and thickness of not less than 12 inches (305 mm), except as otherwise permitted or required in this appendix. Bales used within a continuous wall shall be of consistent height and thickness to ensure even distribution of loads within the wall system. See Figure BJ103.2 for approximate dimensions of common straw bales.

FIGURE BJ103.2—APPROXIMATE DIMENSIONS OF COMMON STRAW BALES

For SI: 1 inch = 25.4 mm.

BJ103.3 Ties.

Bales shall be confined by synthetic fiber, natural fiber or metal ties sufficient to maintain required bale density. Ties shall be not less than 3 inches (76 mm) and not more than 6 inches (152 mm) from the two untied faces and shall be spaced not more than 12 inches (305 mm) apart. Bales with broken ties shall be retied with sufficient tension to maintain required bale density.

BJ103.4 Moisture content.

The moisture content of bales at the time of application of the first coat of plaster or the installation of another finish shall not exceed 20 percent of the weight of the bale. The moisture content of bales shall be determined with a moisture meter designed for use with baled straw or hay, equipped with a probe of sufficient length to reach the center of the bale. Not less than 5 percent and not fewer than 10 bales shall be randomly selected and tested.

BJ103.5 Density.

Bales shall have a dry density of not less than 6.5 pounds per cubic foot (104 kg/cubic meter). The dry density shall be calculated by subtracting the weight of the moisture in pounds (kg) from the actual bale weight and dividing by the volume of the bale in cubic feet (cubic meters). Not less than 2 percent and not fewer than five bales shall be randomly selected and tested on-site.

BJ103.6 Partial bales.

Partial bales made after original fabrication shall be retied with ties complying with Section BJ103.3.

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

APPENDIX BJ — STRAWBALE CONSTRUCTION

BJ103.7 Types of straw.

Bales shall be composed of straw from wheat, rice, rye, barley or oat. The dry stems of other cereal grains or similar crops shall be acceptable where approved by the building official. Bales shall not be composed of hay.

BJ103.8 Orientation of bales.

Straw bales shall be placed laid flat, on-edge or on end in accordance with this appendix.

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▸ Contents — 2025 California Residential Code (Title 24, Part 2.5)
2025 California Residential Code (Title 24, Part 2.5)
  1. Chapter 1 — ADMINISTRATION
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — BUILDING PLANNING
  4. Chapter 4 — FOUNDATIONS
  5. Chapter 5 — FLOORS
  6. Chapter 6 — WALL CONSTRUCTION
  7. Chapter 7 — WALL COVERING
  8. Chapter 8 — ROOF-CEILING CONSTRUCTION
  9. Chapter 9 — ROOF ASSEMBLIES
  10. Chapter 10 — CHIMNEYS AND FIREPLACES
  11. Chapter 44 — REFERENCED STANDARDS
  12. Appendix AA — BOARD OF APPEALS
  13. Appendix AB — PERMIT FEES
  14. Appendix AC — RESERVED
  15. Appendix BA — RESERVED
  16. Appendix BB — TINY HOUSES
  17. Appendix BC — RESERVED
  18. Appendix BD — RESERVED
  19. Appendix BE — RADON CONTROL METHODS
  20. Appendix BF — PATIO COVERS
  21. Appendix BG — SOUND TRANSMISSION
  22. Appendix BH — AUTOMATIC VEHICULAR GATES
  23. Appendix BI — LIGHT STRAW-CLAY CONSTRUCTION
  24. ▸ Appendix BJ — STRAWBALE CONSTRUCTION
    Overview
    1. Section BJ101 — GENERAL
    2. Section BJ102 — DEFINITIONS
    3. Section BJ103 — BALES
    4. Section BJ104 — FINISHES
    5. Section BJ105 — STRAWBALE WALLS—GENERAL
    6. Section BJ106 — STRAWBALE WALLS—STRUCTURAL
    7. Section BJ107 — FIRE RESISTANCE
    8. Section BJ108 — THERMAL INSULATION
    9. Section BJ109 — REFERENCED STANDARDS
  25. Appendix BK — COB CONSTRUCTION (MONOLITHIC ADOBE)
  26. Appendix BL — HEMP-LIME (HEMPCRETE) CONSTRUCTION
  27. Appendix BM — 3D-PRINTED BUILDING CONSTRUCTION
  28. Appendix BN — EXTENDED PLATE WALL CONSTRUCTION
  29. Appendix BO — EXISTING BUILDINGS AND STRUCTURES
  30. Appendix CA — RESERVED
  31. Appendix CB — RESERVED
  32. Appendix CC — RESERVED
  33. Appendix CD — RESERVED
  34. Appendix CE — RESERVED
  35. Appendix CF — RESERVED
  36. Appendix CG — NONSEWERED SANITATION SYSTEMS
  37. Appendix CH — PRIVATE SEWAGE DISPOSAL
  38. Appendix CI — SWIMMING POOL SAFETY ACT
  39. Appendix CJ — EMERGENCY HOUSING
  40. Appendix CK — AREAS PROTECTED BY THE FACILITIES OF THE CENTRAL…

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