Section AU106

AU106.1 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 engineered design.

AU106.2 Requirements for cob structural walls.¶

In addition to the requirements of Section AU105.2, cob structural walls shall be subject to the following:

Wall height: shall be in accordance with Table AU105.3 for load-bearing cob walls or Table AU106.11(1) for cob braced wall panels, as applicable and most restrictive.
Wall thickness: shall be in accordance with Sections AU105.2, Item 5 and Section AU106.8.1 for load-bearing cob walls or Table AU106.11(1) for cob braced wall panels, as applicable and most restrictive.
Braced wall panel lengths: for buildings using cob braced wall panels, the greater of the values determined in accordance with Table AU106.11(2) for wind loads and Table AU106.11(3), AU106.11(4) or AU106.11(5) for seismic loads shall be used.

AU106.3 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 AU-1.

CWDL = ( H × Tavg × D ) (Equation AU-1)

CWDL = Cob wall dead load (in pounds per lineal foot of

wall).

H = Height of cob portion of wall (in feet).

Tavg = 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.

AU106.4 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.

AU106.5 Wall taper, straightness and surface voids for cob walls.¶

cob walls. Cob walls shall be in accordance with the following:

Cob structural and nonstructural walls shall be vertical or shall taper from bottom to top with the wall thickness in accordance with Section AU105.2, Item 5 and the wall height in accordance with Section AU105.2, Item 4.
Cob structural and nonstructural walls shall be straight or curved. Curved braced wall panels shall be in accordance with Sections AU106.11.2 and AU106.11.3.
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 AU106.10 and be reinforced in accordance with Section AU105.3.4. Surface voids are prohibited in braced wall panels.

AU106.6 Compressive strength of cob structural and nonstructural walls.¶

nonstructural walls. All cob walls shall have a minimum compressive strength of 60 psi (414 kPa). Cob in walls used as braced wall panels shall have a minimum compressive strength of 85 psi (586 kPa).

AU106.6.1 Demonstration of compressive strength. The compressive strength of the cob mix to be used in structural walls and nonstructural walls as required in Section

APPENDIX AU-6 2022 CALIFORNIA RESIDENTIAL CODE

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AU106.6 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:

Five samples of the proposed cob mix shall be placed moist to completely fill a 4-inch by 4-inch by 4-inch (102 mm by 102 mm by 102 mm) form and dried to ambient moisture conditions.
Samples shall not be oven dried.
Any opposite faces shall be faced with plaster of paris if needed to achieve smooth, parallel faces, after which the sample shall reach ambient moisture conditions before testing.
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.
The fourth-lowest value shall be used to determine the mix’s compressive strength.

AU106.7 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).

AU106.7.1 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:

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.
Samples shall not be oven dried.
Each sample shall be tested with the 12-inch (305 mm) dimension horizontal.
The fourth-lowest value shall be used to determine if the mix meets the minimum required modulus of rupture.

AU106.8 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 be determined by Equation AU-2.

BC = 144 ( C × Tmin )/3 – ( H × Tavg × D ) (Equation AU-2)

BC = Allowable bearing capacity of wall (in pounds per

lineal foot of wall). C = Compressive strength (in psi) as determined in

accordance with Section AU106.6. Tmin = Thickness of wall (in feet) at its minimum. H = Height of cob portion of wall (in feet). Tavg = 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.

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

AU106.8.1 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 AU-3.

BL ≤ BC (Equation AU-3)

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 AU106.8.

AU106.8.2 Support of concentrated loads. Concentrated roof and ceiling loads shall be distributed by structural elements capable of distributing the loads to the cob loadbearing wall and within its allowable bearing capacity as determined in accordance with Section AU106.8. Concentrated loads over lintels or over bond beams spanning openings shall require an approved engineered design.

AU106.9 Bond beams.¶

Cob structural walls shall require a bond beam at the top of the wall in accordance with Section AU106.9.1, AU106.9.2 or AU106.9.3, and shall be anchored to the cob below in accordance with Tables AU105.3, AU106.11(1) and AU106.12 as applicable and most restrictive. Bond beams spanning openings shall be in accordance with Section AU106.9.4.

AU106.9.1 Wood bond beams. Wood bond beams shall be not less than nominal 4 inches high by 8 inches wide and shall comply with Sections AU106.9.1.1 through AU106.9.1.3.

AU106.9.1.1 Wood species and grade. Wood bond beams shall be of a species with an extreme fiber in bending ( Fb ) 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 Fb of not less than 850 psi (5.9 MPa), and an E of not less than 1,300,000 psi (8964 MPa).

AU106.9.1.2 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:

For seismic design categories: A, 2,500 pounds (11 kN); B, 4,500 pounds (20 kN); C, 6,000 pounds (26.7 kN).
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).

AU106.9.1.3 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 AU106.9.1.2.

AU106.9.2 Concrete bond beams. Concrete bond beams shall be not less than 6 inches (152 mm) high by 8 inches

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

(305 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.

AU106.9.3 Other bond beams. Bond beams of other materials, including earthen materials, require an approved engineered design.

AU106.9.4 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 AU106.10. Bond beams shall be continuous across the opening and not less than 1 foot (305 mm) beyond each side of the opening.

AU106.9.5 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 AU106.9.5. Roof sheathing shall be attached to roof framing in accordance with Figure AU106.9.5. 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.

AU106.9.6 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 AU106.9.6 and the following:

End walls shall not exceed 20 feet (6096 mm) in length.
Bond beams shall be continuous and straight for the entire wall line.
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 AU106.11(2) and where seismic design governs in accordance with Table AU106.11(3), AU106.11(4) or AU106.11(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 AU106.9.3.

FIGURE AU106.9.5 FIGURE AU106.9.5 CONNECTION OF ROOF FRAMING TO BOND BEAMS CONNECTION OF ROOF FRAMING TO BOND BEAMS

APPENDIX AU-8 2022 CALIFORNIA RESIDENTIAL CODE

Concrete bond beams when used shall be in accordance with Section AU106.9.2 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).
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.

AU106.10 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 AU106.10.

AU106.11 Cob braced wall panels.¶

Cob braced wall panels shall be in accordance with Section R602.10 and Tables AU106.11(1), AU106.11(2), AU106.11(3), AU106.11(4) and AU106.11(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.

AU106.11.1 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

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

braced wall lengths in Tables AU106.11(2), AU106.11(3), AU106.11(4) and AU106.11(5), as follows:

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.
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.
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.
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.

AU106.11.2 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 AU106.11(2) and the spacing and length of the braced wall lines for seismic design in Tables AU106.11(3), AU106.11(4) and AU106.11(5) shall be the maximum widths of the building in the two orthogonal directions.

FIGURE AU106.9.6 CONNECTIONS AT GABLE AND SHED ROOF END WALLS

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE AU106.10 LINTELS AND BOND BEAMS SPANNING OPENINGS

GROUND SNOW LOAD ≤ 30 PSF			WOOD: • F ≥ 850 psi b • 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
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
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.

APPENDIX AU-10 2022 CALIFORNIA RESIDENTIAL CODE

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE AU106.11(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 Hd (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 foun- dation 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 rein- forcing)	5/8″ threaded rod; 4″ from each end of braced wall panel and @ 12″; continuous from foun- dation to bond beam	2″ × 2″ × 14 gage welded wire meshf @ 18″; 6″ from foundation and bond beam	7e	2:1
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 Types 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 AU101.4. e. Maximum height shall be 8 feet when wall thickness is increased to 18 inches. f. Galvanized mesh.

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE AU106.11(2) BRACING REQUIREMENTS FOR COB BRACED WALL PANELS BASED ON WIND SPEED

• 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
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 AU106.11 and Table AU106.11(1).

TABLE AU106.11(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 AU106.11(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 AU106.11(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 AU106.11(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 AU106.11(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

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 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 wall panel types indicated shall comply with Section AU106.11 and Table AU106.11(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 International 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.

APPENDIX AU-12 2022 CALIFORNIA RESIDENTIAL CODE

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE AU106.11(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 AU106.11(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
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
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

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 AU106.11 and Table AU106.11(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 International 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. Substitute ¹⁵ /32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).

SDS value is determined in accordance with Section 1613 of the International 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. Substitute ¹⁵ /32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

TABLE AU106.11(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 AU106.11(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
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
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

allowable where a site-specific SDS value is determined in accordance with Section 1613 of the International 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. Substitute ¹⁵ /32″ roof sheathing and 10d at 6″ edge nailing for requirements in Table R602.3(1).

APPENDIX AU-14 2022 CALIFORNIA RESIDENTIAL CODE

AU106.11.3 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 AU106.11(1) and of the length determined in accordance with Section AU106.11. 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 AU106.11.3 and determined by Equation AU-4.

ARCC = 0.0175 RC × A (Equation AU-4)

ARCC = Length of arc at center of wall (in feet). RC = Radius at center of wall = Ri + 0.5 T (in feet). Ri = 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).

AU106.12 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 AU106.12.

AU106.13 Post-and-beam with cob infill.¶

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

APPENDIX AU—COB CONSTRUCTION (MONOLITHIC ADOBE)

AU106.14 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.