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Appendix BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

Section BK106 — COB WALLS—STRUCTURAL

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.

BK106.1 General.

Cob structural walls shall be in accordance with the prescriptive provisions of this section. Designs or portions of designs not complying with this section shall require an approved design by a registered design professional, except where an engineered design is required.

BK106.2 Requirements for cob structural walls.

In addition to the requirements of Section BK105.2, cob structural walls shall be subject to the following:

  1. Wall height: shall be in accordance with Table BK105.3 for load-bearing cob walls or Table BK106.11(1) for cob braced wall panels, as applicable and most restrictive.
  2. Wall thickness: shall be in accordance with Sections BK105.2, Item 5 and Section BK106.8.1 for load-bearing cob walls or Table BK106.11(1) for cob braced wall panels, as applicable and most restrictive.
  3. Braced wall panel lengths: for buildings using cob braced wall panels, the greater of the values determined in accordance with Table BK106.11(2) for wind loads and Table BK106.11(3), BK106.11(4) or BK106.11(5) for seismic loads shall be used.

BK106.3 Loads and other limitations.

Live and dead loads and other limitations shall be in accordance with Section R301, except that the dead load for cob walls shall be determined by Equation BK-1.

Equation BK-1 CW DL = ( H × T avg × D ) CW DL = Cob wall dead load (in pounds per lineal foot of wall).

H = Height of cob portion of wall (in feet). T avg = Average thickness of wall (in feet). D = Density of cob = 110 (in pounds per cubic foot), unless a lesser value at equilibrium moisture content is demonstrated to the building official.

BK106.4 Foundations.

Foundations for cob walls shall be in accordance with Chapter 4. The width of foundations for cob walls shall be not less than the width of the cob at its base, excluding finish.

BK106.5 Wall taper, straightness and surface voids for cob walls.

Cob walls shall be in accordance with the following:

  1. Cob structural and nonstructural walls shall be vertical or shall taper from bottom to top with the wall thickness in accordance with Section BK105.2, Item 5 and the wall height in accordance with Section BK105.2, Item 4.

APPENDIX BK-8 2025 CALIFORNIA RESIDENTIAL CODE

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

  1. Cob structural and nonstructural walls shall be straight or curved. Curved braced wall panels shall be in accordance with Sections BK106.11.2 and BK106.11.3.

  2. Niches and other surface voids in load-bearing walls are limited to 12 inches (305 mm) in width and height and 25 percent of the wall thickness, and shall be located in the top two-thirds of the wall. Surface voids that exceed these limits shall be considered wall openings, and shall receive a lintel in accordance with Section BK106.10 and be reinforced in accordance with Section BK105.3.4. Surface voids are prohibited in braced wall panels.

BK106.6 Compressive strength of cob structural and nonstructural walls.

All cob walls shall have a minimum compressive strength of 60 psi (414 kPa), and cob in walls used as braced wall panels shall have a minimum compressive strength of 85 psi (586 kPa), except with an approved engineered design.

BK106.6.1 Demonstration of compressive strength. The compressive strength of the cob mix to be used in structural walls and nonstructural walls as required in Section BK106.6 shall be demonstrated to the building official before the placement of cob onto walls, with compressive strength tests and an associated report by an approved laboratory or with an approved on-site test as follows:

  1. Five samples of the proposed cob mix shall be placed moist to completely fill a 4-inch by 4-inch by 8-inch (102 mm by 102 mm by 203 mm) form and dried to ambient moisture conditions.
  2. Samples shall not be oven dried.
  3. The 4-inch by 4-inch (102 mm by 102 mm) faces shall be capped with plaster of paris to achieve smooth, parallel faces, after which the sample shall reach ambient moisture conditions before testing.
  4. Samples shall be constructed, dried and tested with the long dimension vertical.
  5. The horizontal cross section of the dried sample as tested, and the maximum applied load at failure shall be used to calculate the sample’s compressive strength.
  6. The fourth-lowest value shall be used to determine the mix’s compressive strength.

BK106.7 Modulus of rupture of cob structural walls.

Cob in walls used as braced wall panels shall have a minimum modulus of rupture of 50 pounds per square inch (345 kPa).

BK106.7.1 Demonstration of modulus of rupture. The modulus of rupture of cob used in structural walls shall be demonstrated to the building official before the placement of cob onto walls, with modulus of rupture tests and an associated report by an approved laboratory or with an approved on-site test as follows:

  1. Five samples of the proposed cob mix shall be placed moist to completely fill a 6-inch by 6-inch by 12-inch (152 mm by 152 mm by 305 mm) form and dried to indoor ambient moisture conditions.
  2. Samples shall not be oven dried.
  3. Each sample shall be tested with the 12-inch (305 mm) dimension horizontal.
  4. The fourth-lowest value shall be used to determine if the mix meets the minimum required modulus of rupture.

BK106.8 Bearing capacity.

The allowable bearing capacity for cob load-bearing walls supporting vertical roof and/or ceiling loads imposed in accordance with Section R301 shall not exceed 2,200 pounds per linear foot (plf) and shall be determined by Equation BK2. Use of bearing capacities determined with Equation BK-2 exceeding 2,200 plf requires an approved design prepared by a registered design professional that accounts for buckling.

Equation BK-2 BC = ( C × T min × 12)/3 – ( H × T avg /12 × D ) BC = Allowable bearing capacity of wall (in pounds per lineal foot of wall).

C = Compressive strength (in psi) as determined in accordance with Section BK106.6.

T min = Thickness of wall (in inches) at its minimum.

H = Height of cob portion of wall (in feet). T avg = Average thickness of wall (in inches). D = Density of cob = 110 (in pounds per cubic foot), unless a lesser value at equilibrium moisture content is demonstrated.

BK106.8.1 Support of uniform loads. Uniform roof and/or ceiling loads shall be supported by cob load-bearing walls not exceeding their allowable bearing capacity, as demonstrated in accordance with Equation BK-3.

Equation BK-3 BL ≤ BC

BL = Design load on the wall (in pounds per lineal foot) determined in accordance with Sections R301.4 and R301.6.

BC = Allowable bearing capacity of wall (in pounds per lineal foot of wall) determined in accordance with Section BK106.8.

BK106.8.2 Support of concentrated loads. Concentrated roof and ceiling loads shall be distributed by structural elements capable of distributing the loads to the cob load-bearing wall and within its allowable bearing capacity as determined in accordance with Section BK106.8. Concentrated loads over lintels or over bond beams spanning openings shall require an approved design by a registered design professional.

BK106.9 Bond beams.

Cob structural walls shall require a bond beam at the top of the wall in accordance with Section BK106.9.1, BK106.9.2 or BK106.9.3, and shall be anchored to the cob below in accordance with Tables BK105.3, BK106.11(1) and BK106.12, as applicable and most restrictive. Bond beams spanning openings shall be in accordance with Section BK106.9.4.

BK106.9.1 Wood bond beams. Wood bond beams shall be not less than nominal 4 inches (102 mm) high by 8 inches (203 mm) wide and shall comply with Sections BK106.9.1.1 through BK106.9.1.3.

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

BK106.9.1.1 Wood species and grade. Wood bond beams shall be of a species with an extreme fiber in bending ( F b ) of not less than 850 psi (5.9 MPa), a modulus of elasticity ( E ) of not less than 1,300,000 psi (8964 MPa), and No. 2 grade or better. Composite lumber bond beams shall have an F b of not less than 850 psi (5.9 MPa), and an E of not less than 1,300,000 psi (8964 MPa).

BK106.9.1.2 Discontinuity. Discontinuous wood bond beams shall be spliced on top with a metal strap with not less than the allowable wind or seismic load tension capacity in accordance with the following, whichever is more restrictive:

  1. For seismic design categories: A, 2,500 pounds (11 kN); B, 4,500 pounds (20 kN); C, 6,000 pounds (26.7 kN).
  2. For braced wall line lengths, when wind governs: 10 feet, 2,500 pounds (11 kN); 20 feet, 3,400 pounds (15.1 kN); 30 feet, 5,000 pounds (22.2 kN).

BK106.9.1.3 Corners and curved walls. Wood bond beams at corners and discontinuities atop curved walls shall be connected across their exterior faces with a metal strap with a capacity of not less than that determined in accordance with Section BK106.9.1.2.

BK106.9.2 Concrete bond beams. Concrete bond beams shall be not less than 6 inches (152 mm) high by 8 inches (203 mm) wide. Concrete bond beams shall be reinforced with two No. 4 bars, 2 inches (51 mm) clear from the bottom and 2 inches (51 mm) clear from the sides. Lap splices shall comply with Table R608.5.4(1). Reinforcing at corners shall be in accordance with the horizontal reinforcing requirements in Section R608.6.4. The concrete shall have a compressive strength of not less than 2,500 pounds per square inch (17.2 MPa) at 28 days.

BK106.9.3 Other bond beams. Bond beams of other materials, including earthen materials, require an approved engineered design.

BK106.9.4 Bond beams spanning openings. Bond beams that support uniform roof and/or ceiling loads and span openings in cob walls shall be in accordance with Table BK106.10. Bond beams shall be continuous across the opening and not less than 1 foot (305 mm) beyond each side of the opening.

BK106.9.5 Connection of roof framing to bond beams. Roof and ceiling framing shall be attached to bond beams in accordance with Table R602.3(1), Items 2 and 6, and Figure BK106.9.5. Roof sheathing shall be attached to roof framing in accordance with Figure BK106.9.5. A minimum nominal 2-inch by 6-inch (51 mm by 152 mm) wood plate shall be installed on concrete bond beams with [5] / 8 -inch (16 mm) diameter anchor bolts with 5-inch (127 mm) embedment at 2 feet (610 mm) on center to allow the required fastening of roof and ceiling framing, including tension ties and straps.

FIGURE BK106.9.5—CONNECTION OF ROOF FRAMING TO BOND BEAMS

BK106.9.6 Bond beams and connections at gable and shed roof end walls. Bond beams and connections at end walls of buildings with gable or shed roofs shall comply with Figure BK106.9.6 and the following:

  1. End walls shall not exceed 20 feet (6096 mm) in length.
  2. Bond beams shall be continuous and straight for the entire wall line.
  3. Wood bond beams shall comply with the following: 3.1. Not less than nominal 4 inches by 8 inches (102 mm by 203 mm) where wind design governs in accordance with Table BK106.11(2) and where seismic design governs in accordance with Table BK106.11(3), BK106.11(4) or

APPENDIX BK-10 2025 CALIFORNIA RESIDENTIAL CODE

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

BK106.11(5) for wall lengths less than or equal to 20 feet (6096 mm) in Seismic Design Category A or wall lengths less than or equal to 10 feet (3048 mm) in Seismic Design Categories B and C. 3.2. Not less than nominal 4 inches by 10 inches (102 mm by 254 mm) for wall lengths less than or equal to 20 feet (6096 mm) in Seismic Design Category B. 3.3. Not less than nominal 6 inches by 12 inches (152 mm by 305 mm) or 4 inches by 16 inches (102 mm by 406 mm) for wall lengths less than or equal to 20 feet (6096 mm) in Seismic Design Category C.

3.4. Corners shall be connected in accordance with Section BK106.9.3.

  1. Concrete bond beams when used shall be in accordance with Section BK106.9.2 in Seismic Design Categories A, B and C and for ultimate design wind speeds less than or equal to 140 mph (63.6 m/s).

  2. Walls between the bond beam and roof shall be of wood-framed construction in accordance with Section R602. The ratio of its greatest height to its length shall not exceed 1:2. The wall shall not contain openings.

FIGURE BK106.9.6—CONNECTIONS AT GABLE AND SHED ROOF END WALLS

ROOF SHEATHING NAILING PER TABLE R602.3(1)

BARGE RAFTER

WHERE OCCURS

CEILING JOISTS, WHERE OCCUR

BOND BEAM PER SECTION BK106.9.6.

WOOD BOND BEAM SHOWN. FOR

CONCRETE BOND BEAM INSTALL WOOD

GABLE AND SHED ROOF END WALL

CONDITION SHOWN. SIMILAR FOR TALL

WALL SUPPORTING A SHED ROOF WITH

WOOD-FRAMED WALL BETWEEN ROOF

RAFTERS AND BOND BEAM OF COB WALL.

BK106.10 Lintels.

Door, window and other openings in load-bearing cob walls shall be provided with a lintel of wood or concrete in accordance with Table BK106.10.

TABLE BK106.10—LINTELS AND BOND BEAMS SPANNING OPENINGS

GROUND SNOW LOAD ≤ 30 PSF GROUND SNOW LOAD ≤ 30 PSF GROUND SNOW LOAD ≤ 30 PSF WOOD:
•
Fb ≥ 850 psi
•
E ≥ 1,300,000 psi
•
No. 2 Grade or better
•
Oriented flat
•
1 piece or 2 equal-width pieces
•
Extend 1 foot beyond opening sides		 WOOD:
•
Fb ≥ 850 psi
•
E ≥ 1,300,000 psi
•
No. 2 Grade or better
•
Oriented flat
•
1 piece or 2 equal-width pieces
•
Extend 1 foot beyond opening sides		 CONCRETE:
•
2500 psi compressive strength
•
Height = 6 inches
•
Extend 1 foot beyond opening sides
•
Reinforcement two No. 4 barsa
•
2 inches clear from bottom
•
2 inches clear from sidesa		 CONCRETE:
•
2500 psi compressive strength
•
Height = 6 inches
•
Extend 1 foot beyond opening sides
•
Reinforcement two No. 4 barsa
•
2 inches clear from bottom
•
2 inches clear from sidesa
Building
width (feet)		 Cob above
lintel (feet)		 Total cob wall
and plaster
thickness
(inches)		 Size of wood lintel or bond beam—H ×W
(nominal inches)		 Size of wood lintel or bond beam—H ×W
(nominal inches)		 Width of concrete lintel or bond beam
(inches)		 Width of concrete lintel or bond beam
(inches)
Building
width (feet)		 Cob above
lintel (feet)		 Total cob wall
and plaster
thickness
(inches)		 For span ≤ 4 ft For span ≤ 6 ft For span ≤ 6 ft For span ≤ 8 ft
10 0 ≤ 27 4 × 8 4 × 8 8 8
10 1 15 4 × 12 4 × 12 12 12
10 1 19 4 × 16 4 × 16 16 16
10 1 27 4 × 24 4 × 24 24 24
10 2 15 4 × 12 6 × 12 12 12
10 2 19 4 × 16 6 × 16 16 16
10 2 27 4 × 24 4 × 24 24 24

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE BK106.10—LINTELS AND BOND BEAMS SPANNING OPENINGS—continued

GROUND SNOW LOAD ≤ 30 PSF GROUND SNOW LOAD ≤ 30 PSF GROUND SNOW LOAD ≤ 30 PSF WOOD:
•
_F_b ≥ 850 psi
•
E ≥ 1,300,000 psi
•
No. 2 Grade or better
•
Oriented flat
•
1 piece or 2 equal-width pieces
•
Extend 1 foot beyond opening sides		 WOOD:
•
_F_b ≥ 850 psi
•
E ≥ 1,300,000 psi
•
No. 2 Grade or better
•
Oriented flat
•
1 piece or 2 equal-width pieces
•
Extend 1 foot beyond opening sides		 CONCRETE:
•
2500 psi compressive strength
•
Height = 6 inches
•
Extend 1 foot beyond opening sides
•
Reinforcement two No. 4 barsa
•
2 inches clear from bottom
•
2 inches clear from sidesa		 CONCRETE:
•
2500 psi compressive strength
•
Height = 6 inches
•
Extend 1 foot beyond opening sides
•
Reinforcement two No. 4 barsa
•
2 inches clear from bottom
•
2 inches clear from sidesa
Building
width (feet)		 Cob above
lintel (feet)		 Total cob wall
and plaster
thickness
(inches)		 Size of wood lintel or bond beam—H ×W
(nominal inches)		 Size of wood lintel or bond beam—H ×W
(nominal inches)		 Width of concrete lintel or bond beam
(inches)		 Width of concrete lintel or bond beam
(inches)
Building
width (feet)		 Cob above
lintel (feet)		 Total cob wall
and plaster
thickness
(inches)		 For span ≤ 4 ft For span ≤ 6 ft For span ≤ 6 ft For span ≤ 8 ft
20 0 ≤ 27 4 × 8 6 × 8 8 8
20 1 15 4 × 12 6 × 12 12 12
20 1 19 4 × 16 6 × 16 16 16
20 1 27 4 × 24 4 × 24 24 24
20 2 15 4 × 12 6 × 12 12 NP
20 2 19 4 × 16 6 × 16 16 NP
20 2 27 4 × 24 6 × 24 24 NP
30 0 ≤ 27 4 × 8 6 × 8 8 NP
30 1 15 4 × 12 6 × 12 12 NP
30 1 19 4 × 13 6 × 16 16 NP
30 1 27 4 × 24 6 × 24 24 NP
30 2 15 4 × 12 6 × 12 12 NP
30 2 19 4 × 16 6 × 16 16 NP
30 2 27 4 × 24 6 × 24 24 NP
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPA.
NP = Not Permitted.
a.
Concrete bond beams spanning openings, and lintels greater than 16 inches in width, shall have an additional No. 4 bar in the center of their width.

BK106.11 Cob braced wall panels.

Cob braced wall panels shall be in accordance with Section R602.10 and Tables BK106.11(1), BK106.11(2), BK106.11(3), BK106.11(4) and BK106.11(5). Wind design criteria shall be in accordance with Section R301.2.1. Seismic design criteria shall be in accordance with Section R301.2.2. An approved engineered design shall be required in accordance with Section R301.2.1 where the building is located in a special wind region or where wind design is required in accordance with Figure R301.2.1.1.

TABLE BK106.11(1)—COB BRACED WALL PANEL TYPES

WALL TYPEa
DESIGNATION		 ANCHORS TO
FOUNDATIONb		 ANCHORS TO
BOND BEAMc		 VERTICAL STEEL
REINFORCINGb, c		 HORIZONTAL STEEL
REINFORCING		 MAXIMUM
HEIGHT_H_d
(in feet)		 MAXIMUM
ASPECT
RATIO (H:L)
A none 5/8″ threaded rod @ 12″;
4″ from wall ends;
12″ embedment in cob		 none none 7e 1:1
B #5 bar @ 12″;
16″ embedment in cob		 5/8″ threaded rod @ 12″;
4″ from wall ends;
16″ embedment in cob;
2″ × 2″ ×1/4″ washer and
nut at cob end		 none 2″ × 2″ × 14 gage welded
wire meshf @ 18″;
6″ from foundation and
bond beam		 7e 1:1
C #5 bar @ 12″;
16″ embedment in cob		 5/8″ threaded rod @ 12″;
16″ embedment in cob		 5/8″ threaded rod;
4″ from each end of
braced wall panel;
continuous from founda-
tion to bond beam		 2″ × 2″ × 14 gage welded
wire meshf @ 18″;
6″ from foundation and
bond beam		 7e 2:1
D (see vertical steel
reinforcing)		 (see vertical steel
reinforcing)		 5/8″ threaded rod;
4″ from each end of
braced wall panel and @
12″; continuous from
foundation to bond beam		 2″ × 2″ × 14 gage welded
wire meshf @ 18″;
6″ from foundation and
bond beam		 7e 2:1

APPENDIX BK-12 2025 CALIFORNIA RESIDENTIAL CODE

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE BK106.11(1)—COB BRACED WALL PANEL TYPES—continued

WALL TYPEa
DESIGNATION		 ANCHORS TO
FOUNDATIONb		 ANCHORS TO
BOND BEAMc		 VERTICAL STEEL
REINFORCINGb, c		 HORIZONTAL STEEL
REINFORCING		 MAXIMUM
HEIGHT_H_d
(in feet)		 MAXIMUM
ASPECT
RATIO (H:L)
E 6″ × 6″× 6 gage welded
wire mesh;
12″ embedment in
foundation		 5/8″ threaded rod @ 12″;
4″ from wall ends;
12″ embedment in cob		 6″ × 6″ × 6 gage welded
wire mesh;
2″ from each wall face		 none 7.5 1:1
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
a. Braced wall panel_T_ypes A, B, C and D shall be not less than 16 inches thick. Braced wall panel Type E shall be not less than 12 inches thick. All braced wall panels shall be not
greater than 24 inches thick.
b. Not less than 8-inch embedment into foundation, unless otherwise stated.
c. Not less than 4-inch embedment into concrete bond beams. Full penetration through wood bond beam, secured with nut and washer.
d.H = height of the cob portion of the wall only. See Figure BK101.4.
e. Maximum height shall be 8 feet when wall thickness is increased to 18 inches.
f. Galvanized mesh.

TABLE BK106.11(2)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON WIND SPEED

TABLE BK106.11(1)—COB BRACED WALL PANEL TYPES—continued

•
EXPOSURE CATEGORY Bd
•
25-FOOT MEAN ROOF HEIGHT
•
10-FOOT EAVE-TO-RIDGE HEIGHTd
•
10-FOOT WALL HEIGHTd
•
2 BRACED WALL LINESd		 •
EXPOSURE CATEGORY Bd
•
25-FOOT MEAN ROOF HEIGHT
•
10-FOOT EAVE-TO-RIDGE HEIGHTd
•
10-FOOT WALL HEIGHTd
•
2 BRACED WALL LINESd		 •
EXPOSURE CATEGORY Bd
•
25-FOOT MEAN ROOF HEIGHT
•
10-FOOT EAVE-TO-RIDGE HEIGHTd
•
10-FOOT WALL HEIGHTd
•
2 BRACED WALL LINESd		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED
WALL PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED
WALL PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED
WALL PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED
WALL PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d
Ultimate design
wind speed
(mph)		 Story
location		 Braced
wall line
spacing
(feet)		 Cob braced
wall panele A;
(aspect ratioH:****L ≤ 1:1)		 Cob braced
wall panele B;
(aspect ratioH:****L ≤ 1:1)		 Cob braced
wall panele C, D;
(aspect ratioH:****L ≤ 2:1)		 Cob braced
wall panele E;
(aspect ratioH:****L≤ 1:1)
≤ 110 One-story building 10 6.0 6.0 3.7 6.0
≤ 110 One-story building 20 7.9 7.4 7.4 6.0
≤ 110 One-story building 30 11.8 11.0 11.0 6.9
≤ 115 One-story building 10 6.0 6.0 4.1 6.0
≤ 115 One-story building 20 8.7 8.1 8.1 6.0
≤ 115 One-story building 30 13.0 12.1 12.1 7.6
≤ 120 One-story building 10 6.0 6.0 4.4 6.0
≤ 120 One-story building 20 9.4 8.8 8.8 6.0
≤ 120 One-story building 30 14.1 13.1 13.1 8.3
≤ 130 One-story building 10 6.0 6.0 5.1 6.0
≤ 130 One-story building 20 11.0 10.3 10.3 6.5
≤ 130 One-story building 30 16.5 15.4 15.4 9.7
≤ 140 One-story building 10 6.0 6.0 5.9 6.0
≤ 140 One-story building 20 12.7 11.9 11.9 7.5
≤ 140 One-story building 30 19.1 17.8 17.8 11.2
For SI: 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s.
a. Linear interpolation shall be permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable wind adjustment factors associated with Items 1 and 2 of Table R602.10.3(2).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE BK106.11(3)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY A

•
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SEISMIC DESIGN CATEGORY A
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SEISMIC DESIGN CATEGORY A
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SEISMIC DESIGN CATEGORY A
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SEISMIC DESIGN CATEGORY A
•
1.5″ PLASTER THICKNESS EACH SIDEg		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e
Braced wall
line spacing
(feet)		 Braced wall
line length
(feet)		 Min. braced wall line
% openings		 Min. perpendicular
braced wall line %
openings		 Cob braced
wall panele A, B		 Cob braced
wall panele C, D		 Cob braced
wall panele E
10 30 0 0 — 3.4 6.0
20 20 0 0 — 3.5 6.0
20 30 0 0 — 4.5 6.0
30 30 0 0 — 5.6 6.0

TABLE BK106.11(3)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY A

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.

TABLE BK106.11(3)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY A g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panelTypes C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced wall panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thickness between 3 inches and 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.|

TABLE BK106.11(3)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY A

TABLE BK106.11(4)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY B

•
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e
Braced wall
line spacing
(feet)		 Braced wall
line length
(feet)		 Min. braced wall
line % openings		 Min. perpendicular
braced wall lines %
openings		 Cob braced
wall panele A, B		 Cob braced
wall panele C, D		 Cob braced
wall panele E
10 10 0 0 6.0 3.2 6.0
10 20 0 0 6.0 4.9 6.0
10 20 50 0 6.0 3.5 6.0
10 30 0 0 7.1 6.6 6.0
10 30 50 0 6.0 4.5 6.0
20 10 0 0 6.0h 4.9h 6.0
20 10 0 50 6.0 3.5 6.0
20 10 50 0 NP 4.2 NP
20 10 50 50 NP 3.0 NP
20 20 0 0 7.4 6.9 6.0
20 20 0 50 6.0 5.5 6.0
20 20 50 0 6.0 5.5 6.0
20 20 50 50 6.0 4.1 6.0
20 30 0 0 9.4 8.8 6.0
20 30 0 50 7.9 7.4 6.0
20 30 50 0 7.2 6.7 6.0
20 30 50 50 6.0 5.3 6.0
30 10 0 0 7.1 6.6 6.0
30 20 0 0 9.4 8.8 6.0

APPENDIX BK-14 2025 CALIFORNIA RESIDENTIAL CODE

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE BK106.11(4)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY B—continued

•
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY B
•
1.5″ PLASTER THICKNESS EACH SIDEg		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e
Braced wall
line spacing
(feet)		 Braced wall
line length
(feet)		 Min. braced wall
line % openings		 Min. perpendicular
braced wall lines %
openings		 Cob braced
wall panele A, B		 Cob braced
wall panele C, D		 Cob braced
wall panele E
30 20 0 50 7.2 6.7 6.0
30 20 50 0 7.9 7.4 6.0
30 30 0 0 11.8 11.0 6.0
30 30 0 50 9.5 8.9 6.0
30 30 50 0 9.5 8.9 6.0
30 30 50 50 7.3 6.8 6.0

TABLE BK106.11(4)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY B—continued

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.

TABLE BK106.11(4)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY B—continued a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3 inches to 6 inches, the minimum total length of braced wall panels shall be multiplied by 1.2.
h. Total plaster thicknesses shall be not greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).|

TABLE BK106.11(4)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY B—continued

TABLE BK106.11(5)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY C

•
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e
** Braced wall**
line spacing
(feet)		 ** Braced wall**
line length
(feet)		 ** Min. braced wall**
line % openings		 ** Min. perpendicular**
braced wall lines %
openings		 Cob braced wall
panele A, B		 Cob braced wall
panele C, D		 Cob braced wall
panele E
10 10 0 0 8.3h 7.8h 6.0
10 10 0 50 6.5 6.1 6.0
10 10 25 0 7.4h 6.9h 6.0
10 10 50 50 NP 4.4 6.0
10 15 0 0 10.6 9.9 6.0
10 15 0 50 8.7 8.2 6.0
10 15 50 0 NP 7.3 6.0
10 15 50 50 6.0 5.6 6.0
10 20 0 0 12.8 11.9 6.0
10 20 0 50 11.0 10.2 6.0
10 20 50 0 9.1 8.5 6.0
10 20 50 50 7.3 6.8 6.0
15 10 25 0 NP NP 6.0h
15 10 0 50 7.8 7.3 6.0
15 10 50 0 NP NP NP
15 10 50 50 NP NP NP
15 15 0 0 12.9 12.1 6.0
15 15 0 50 10.2 9.5 6.0
15 15 50 0 NP NP 6.0

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE BK106.11(5)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY C

•
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 •
SOIL CLASS Df
•
TOTAL WALL HEIGHT = 10 FEET (INCLUDING STEM WALL AND BOND BEAM)
•
COB WALL HEIGHT PER TABLE BK106.11(1)
•
15 PSF ROOF-CEILING DEAD LOADd
•
STORY LOCATION: ONE-STORY BUILDING
•
SESIMIC DESIGN CATEGORY C
•
1.5″ PLASTER THICKNESS EACH SIDEg		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e		 MINIMUM TOTAL LENGTH (feet) OF COB BRACED WALL
PANELS REQUIRED ALONG EACH BRACED WALL LINEa, b, c, d, e
** Braced wall**
line spacing
(feet)		 ** Braced wall**
line length
(feet)		 ** Min. braced wall**
line % openings		 ** Min. perpendicular**
braced wall lines %
openings		 Cob braced wall
panele A, B		 Cob braced wall
panele C, D		 Cob braced wall
panele E
15 15 50 50 7.5 7.0 6.0
15 20 0 0 15.3 14.3 6.0
15 20 0 50 12.6 11.7 6.0
15 20 50 0 NP NP 6.0
15 20 50 50 8.9 8.3 6.0
20 10 25 0 NP NP NP
20 10 0 50 9.1 8.5 6.0
20 10 50 0 NP NP NP
20 10 50 50 NP NP NP
20 15 0 0 NP 14.3h 6.0h
20 15 0 50 11.7h 10.9h 6.0
20 15 50 0 NP NP 6.0h
20 15 50 50 NP NP 6.0
20 20 0 0 17.8 16.7 6.9
20 20 0 50 14.2 13.3 6.0
20 20 50 0 NP NP 6.0
20 20 50 50 NP 9.9 6.0

TABLE BK106.11(5)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY C

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).		 For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.

TABLE BK106.11(5)—BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON SEISMIC DESIGN CATEGORY C c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square foot = 0.0479 kPa.
NP = Not Permitted.
a. Interpolation is not permitted.
b. Braced wall panels shall be without openings.
c. Braced wall panel Types A, B and E shall have an aspect ratio (H:L) ≤ 1:1. Braced wall panel Types C and D shall have an aspect ratio (H:L) ≤ 2:1.
d. Subject to applicable seismic adjustment factors associated with Item 5 in Table R602.10.3(4).
e. Cob braced panel types indicated shall comply with Section BK106.11 and Table BK106.11(1).
f. Wall bracing lengths are based on a soil site class D. Interpolation of bracing lengths between_SDS_ values associated with the seismic design categories is allowable where a
site-specific_SDS_ value is determined in accordance with Section 1613 of the_California Building Code_.
g. For total plaster thicknesses 3″ to 6″, multiply the minimum total length of braced wall panels by 1.2.
h. Total plaster thickness shall not be greater than 3 inches. Substitute15/32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).|

BK106.11.1 Nonorthogonal braced wall panels. Braced wall panels at an angle to the orthogonal braced wall lines shall be considered to contribute to the minimum total braced wall lengths in Tables BK106.11(2), BK106.11(3), BK106.11(4) and BK106.11(5), as follows:

  1. A braced wall panel not more than 45 degrees and greater than 30 degrees to an adjacent orthogonal braced wall line shall contribute 50 percent of its length to that line.

  2. A braced wall panel not more than 30 degrees to an orthogonal braced wall line shall contribute 65 percent of its length to that line.

  3. A braced wall panel greater than 45 degrees and not more than 60 degrees to an orthogonal braced wall line shall contribute 35 percent of its length to that line.

  4. The angle of a curved braced wall panel to a braced wall line shall be determined with the chord of that section of wall, connecting the end points of the arc at the center of the wall.

BK106.11.2 Braced wall lines for buildings with curved walls. Buildings with curved cob walls shall contain two braced wall lines in two orthogonal directions. The spacing of the braced wall lines for wind design in Table BK106.11(2) and the spacing and length of the braced wall lines for seismic design in Tables BK106.11(3), BK106.11(4) and BK106.11(5) shall be the maximum widths of the building in the two orthogonal directions.

BK106.11.3 Radius, thickness and length of curved braced wall panels. Cob curved braced wall panels shall have an inside radius of not less than 5 feet (1524 mm), shall be of the thickness required in Table BK106.11(1) and of the length determined in accordance with Section BK106.11. The length of the curved wall shall be considered to be the length of the arc at the center of the wall, in accordance with Figure BK106.11.3 and determined by Equation BK-4.

Equation BK-4 ARC C = 0.0175 R C × A

APPENDIX BK-16 2025 CALIFORNIA RESIDENTIAL CODE

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

ARC C = Length of arc at center of wall (in feet). R C = Radius at center of wall = R i + 0.5 T (in feet). R i = Inside radius of wall (in feet).

T = Thickness of wall without finish (in feet).

A = Angle of extent of braced wall panel from the center of the arc (in degrees).

FIGURE BK106.11.3—CURVED BRACED WALL PANEL

BK106.12 Resistance to wind uplift forces.

Cob walls that resist uplift forces from the roof assembly, as determined in accordance with Section R802.11, shall be in accordance with Table BK106.12.

TABLE BK106.12—ANCHORAGE OF BOND BEAMS FOR WIND UPLIFT
ANCHORS:
•
5/8″ ALL THREAD AT 12″ O.C.a, b
•
2″ × 2″ ×1/4″ WASHERS AND NUT AT END IN COB
•
4″ EMBEDMENT IN CONCRETE BOND BEAMS
•
FULL PENETRATION THROUGH WOOD BOND BEAMS WITH 2″ × 2″ ×1/4″ WASHER AND NUT
WIND UPLIFT FORCE
FROM TABLE R802.11
(plf)		 ANCHORAGE DEPTH IN INCHES, PER WALL WIDTH AND WIND UPLIFT FORCE ANCHORAGE DEPTH IN INCHES, PER WALL WIDTH AND WIND UPLIFT FORCE ANCHORAGE DEPTH IN INCHES, PER WALL WIDTH AND WIND UPLIFT FORCE
WIND UPLIFT FORCE
FROM TABLE R802.11
(plf)		 ≤ 12″
wall widthc		 ≤ 16″
wall widthc		 ≤ 24″
wall widthc
< 75 16 12 12
< 100 24 16 12
< 150 48 o.c. continuous from foundation to bond beamd 24 16
< 200 48 o.c. continuous from foundation to bond beamd 48 o.c. continuous from foundation to bond beamd 24
For SI: 1 inch = 25.4 mm.
a. For wood bond beams a maximum of 6 inches from bond beam ends.
b. For minimum 6-inch by 8-inch concrete bond beams, at 18″ o.c. for wind uplift forces less than 75 pounds per linear foot, and at 16″ o.c. for wind uplift forces less than 100
pounds per linear foot.
c. Excluding finishes.
d. With 7-inch embedment in foundation, 4-inch embedment in concrete bond beam or full penetration through wood bond beam with 2-inch by 2-inch by1/4-inch washer and nut.

BK106.13 Post-and-beam with cob infill.

Post-and-beam with cob infill wall systems shall be in accordance with an approved engineered design.

BK106.14 Buttresses.

Cob buttresses that are intended to provide out-of-plane wall bracing or additional capacity for braced wall panels shall be in accordance with an approved engineered design.

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

APPENDIX BK — COB CONSTRUCTION (MONOLITHIC ADOBE)

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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
  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…

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