Skip to content

Appendix BJ — STRAWBALE CONSTRUCTION

Section BJ107 — FIRE RESISTANCE

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.

BJ107.1 Fire-resistance rating.

Strawbale walls shall not be considered to exhibit a fire-resistance rating, except for walls constructed in accordance with Section BJ107.1.1 or BJ107.1.2. Alternately, fire-resistance ratings of strawbale walls shall be determined in accordance with Section R302.

BJ107.1.1 One-hour-rated clay-plastered wall. One-hour fire-resistance-rated nonload-bearing clay plastered strawbale walls shall comply with all of the following:

  1. Bales shall be laid flat or on-edge in a running bond.
  2. Bales shall maintain thickness of not less than 18 inches (457 mm).
  3. Bales shall have a minimum dry density of 7.25 pounds per cubic foot (116 kg/m [3] ).
  4. Gaps shall be stuffed with straw-clay.
  5. Clay plaster on each side of the wall shall be not less than 1 inch (25 mm) thick and shall be composed of a mixture of 3 parts clay, 2 parts chopped straw and 6 parts sand, or an alternative approved clay plaster.
  6. Plaster application shall be in accordance with Section BJ104.4.3.3 for the number and thickness of coats.

BJ107.1.2 Two-hour-rated cement-plastered wall. Two-hour fire-resistance-rated nonload-bearing cement-plastered strawbale walls shall comply with all of the following:

  1. Bales shall be laid flat or on-edge in a running bond.
  2. Bales shall maintain a thickness of not less than 14 inches (356 mm).
  3. Bales shall have a minimum dry density of 7.25 pounds per cubic foot (116 kg/m [3] ).
  4. Gaps shall be stuffed with straw-clay.
  5. A single section of [1] / 2 -inch (38 mm) by 17-gage galvanized woven wire mesh shall be attached to wood members with 1 [1] / 2 -inch (38 mm) staples at 6 inches (152 mm) on center. 9 gage U-pins with not less than 8-inch (203 mm) legs shall be installed at 18 inches (457 mm) on center to fasten the mesh to the bales.
  6. Cement plaster on each side of the wall shall be not less than 1 inch (25 mm) thick.
  7. Plaster application shall be in accordance with Section BJ104.4.9 for the number and thickness of coats.

BJ107.2 Openings in rated walls.

Openings and penetrations in bale walls required to have a fire-resistance rating shall satisfy the same requirements for openings and penetrations as prescribed in this code.

BJ107.3 Clearance to fireplaces and chimneys.

Strawbale surfaces adjacent to fireplaces or chimneys shall be finished with not less than [3] / 8 -inch-thick (10 mm) plaster of any type permitted by this appendix. Clearance from the face of such plaster to fireplaces and chimneys shall be maintained as required from fireplaces and chimneys to combustibles in Chapter 10, or as required by manufacturer’s instructions, whichever is more restrictive.

Get a plain-English answer with a citation back to this text.

Ask AI about this code
▸ 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…

GoCodebook provides public access, search, citation, multilingual explanation, and practical interpretation of legally adopted building regulations. It is not a substitute for the official ICC or California code publications.