Skip to content

Appendix BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

Section BK102 — DEFINITIONS

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.

BK102.1 Definitions.

The words and terms in this section shall, for the purposes of this appendix, have the meanings shown herein. Refer to Chapter 2 for general definitions.

BRACED WALL PANEL. A cob wall designed and constructed to resist in-plane shear loads through the interaction of the cob material, its reinforcing and its connections to its bond beam and foundation. The panel’s length meets the requirements for the particular wall type and contributes toward the total amount of bracing required along its braced wall line in accordance with Sections BK106.11 and R602.10.1.

BUCK. A frame, typically wood, anchored in a wall system, that creates the rough opening into which a window or door frame is installed.

BUTTRESS. A mass set at an angle to or bonded to a wall that it strengthens or supports.

CLAY. Inorganic soil with particle sizes less than 0.00008 inch (0.002 mm) and having the characteristics of high to very high dry strength and medium to high plasticity, used as the binder of other component materials in a mix of cob or of clay plaster.

CLAY SUBSOIL. Subsoil sourced directly from the earth, containing clay, sand and silt, and containing not more than trace amounts of organic matter.

COB. A composite building material consisting of refined clay or clay subsoil wet-mixed with loose straw and sometimes sand.

COB CONSTRUCTION. A wall system of layers or lifts of moist cob placed to create monolithic walls, typically without formwork. Also known as “Monolithic adobe.”

DRY JOINT. The boundary between a layer of moist cob and a previously laid and significantly drier, nonmalleable layer of cob that requires wetting to achieve bonding between the layers.

FINISH. Completed combination of materials on the face of a cob wall.

LIFT. A layer of installed cob.

LOAD-BEARING WALL. A cob wall that supports more than 100 pounds per linear foot (1459 N/m) of vertical load in addition to its own weight.

MONOLITHIC ADOBE. See “Cob construction.”

NATURAL COB. Cob not containing admixtures such as Portland cement, lime, asphalt emulsion or oil. Synonymous with “ Unstabi- lized cob .”

NONSTRUCTURAL WALL. Walls other than load-bearing walls or shear walls.

PLASTER. Clay, soil-cement, gypsum, lime, clay-lime, cement-lime or cement plaster as described in Section BK104.

SHEAR WALL. A cob wall designed and constructed to resist in-plane lateral seismic and wind forces in accordance with Section BK106.11. Synonymous with “Braced wall panel.”

STABILIZED. Cob or other earthen material containing admixtures, such as Portland cement, lime, asphalt emulsion or oil, that are intended to help limit water absorption, stabilize volume, increase strength and increase durability.

STRAW. The dry stems of cereal grains after the seed heads have been removed.

STRUCTURAL WALL. A wall that meets the definition for a “Load-bearing wall” or “Shear wall.”

UNSTABILIZED. Cob or other earthen material that does not contain admixtures such as Portland cement, lime, asphalt emulsion or oil.

UNSTABILIZED COB. See “Natural cob.”

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
  25. ▸ Appendix BK — COB CONSTRUCTION (MONOLITHIC ADOBE)
    Overview
    1. Section BK101 — GENERAL
    2. Section BK102 — DEFINITIONS
    3. Section BK103 — MATERIALS, MIXING AND INSTALLATION
    4. Section BK104 — FINISHES
    5. Section BK105 — COB WALLS—GENERAL
    6. Section BK106 — COB WALLS—STRUCTURAL
    7. Section BK107 — COB FLOORS
    8. Section BK108 — FIRE RESISTANCE
    9. Section BK109 — THERMAL PERFORMANCE
    10. Section BK110 — REFERENCED STANDARDS
  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.