Section AS105

AS105.1 General.¶

Strawbale walls shall be designed and constructed in accordance with this section and with Figures AS105.1(1) through AS105.1(4) or an approved alternative design. Strawbale structural walls shall be in accordance with the additional requirements of Section AS106.

AS105.2 Building limitations and requirements for use of strawbale nonstructural walls.¶

strawbale nonstructural walls. Buildings using strawbale nonstructural walls shall be subject to the following limitations and requirements:

Number of stories: not more than one, except that two stories shall be allowed with an approved engineered design.
Building height: not more than 25 feet (7620 mm), except that greater heights shall be allowed with an approved engineered design.
Wall height: in accordance with Table AS105.4.
Braced wall panel lengths: in accordance with Section R602.10.3, with the additional requirements that Table R602.10.3(3) shall apply to all buildings in Seismic Design Category C, and the minimum total length of braced wall panels in Table R602.10.3(3) shall be increased by 60 percent for buildings in Seismic Design Categories C, D0, D1 and D2.

AS105.3 Sill plates.¶

Sill plates shall be installed in accordance with Figure AS105.1(1) or AS105.1(2). Sill plates shall support and be flush with each face of the straw bales above and shall be of naturally durable or preservative-treated wood where required by this code. Sill plates shall be not less than nominal 2 inches by 4 inches (51 mm by 102 mm) with anchoring complying with Section R403.1.6 and the additional requirements of Table AS105.4, where applicable, and Sections AS106.13.2 and AS106.13.3 for strawbale braced wall panels.

AS105.3.1 Exterior sill plate flashing. Exterior sill plates shall receive flashing across the plate to slab or foundation joints.

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APPENDIX AS—STRAWBALE CONSTRUCTION

For SI: 1 inch = 25.4 mm.

FIGURE AS105.1(1) TYPICAL BASE OF PLASTERED STRAWBALE WALL ON CONCRETE SLAB AND FOOTING

APPENDIX AS-6 2022 CALIFORNIA RESIDENTIAL CODE

For SI: 1 inch = 25.4 mm.

APPENDIX AS—STRAWBALE CONSTRUCTION

FIGURE AS105.1(2) TYPICAL BASE OF PLASTERED STRAWBALE WALL OVER RAISED FLOOR

APPENDIX AS—STRAWBALE CONSTRUCTION

SECTION AS106.11

INSULATION FILL

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound = 2.2 kg.

FIGURE AS105.1(3) TYPICAL TOP OF LOAD-BEARING STRAWBALE WALL

BOUNDARY NAILING PER TABLE R602.3(1)

2X BLOCKING FOR DIRECT BEARING ONTO PLASTER PER SECTION AS106.11

HEADER AT WALL OPENINGS PER TABLE R602.7(1) AND SECTION AS106.12.3

16d NAILS @ 4 ″

MESH STAPLES PER TABLE AS106.13(1) FOR BRACED WALL PANELS FOR WIND UPLIFT PER SECTION AS106.14

MULTIPLE 2X WHERE REQUIRED FOR HEADERS PER TABLE R602.7(1)

PLASTER FOR LOAD-BEARING WALLS PER TABLE AS106.12 AND PER TABLE AS106.13(1) WHERE WALL IS ALSO USED AS A BRACED WALL PANEL

MESH AS REQUIRED PER TABLE AS106.12 OR AS106.13(1) OR SECTION AS106.14

APPENDIX AS-8 2022 CALIFORNIA RESIDENTIAL CODE

ROOF SYSTEM PER CHAPTER 8

PANELS

WALL PANELS

NOTE:

For SI: 1 inch = 25.4 mm.

APPENDIX AS—STRAWBALE CONSTRUCTION

2X BLOCKING PER SECTION AS106.11 FOR BRACED WALL PANELS

AS104.4 OR TABLE AS106.13(1)

FIGURE AS105.1(4) TYPICAL TOP OF POST-AND-BEAM WALL WITH PLASTERED STRAWBALE INFILL

APPENDIX AS—STRAWBALE CONSTRUCTION

AS105.4 Out-of-plane resistance methods and unre-strained wall dimension limits.¶

strained wall dimension limits. Strawbale walls shall employ a method of out-of-plane load resistance in accordance with Table AS105.4, and comply with its associated limits and requirements.

AS105.4.1 Determination of out-of-plane loading. Outof-plane loading for the use of Table AS105.4 shall be in terms of the ultimate design wind speed and seismic design category as determined in accordance with Sections R301.2.1 and R301.2.2. An engineered design in accordance with Section R301.2.1 shall be required where the building is located in a special wind region or where wind design is required in accordance with Figure R301.2(2) and Section R301.2.1.1, respectively.

AS105.4.2 Pins. Pins used for out-of-plane resistance shall comply with the following or shall be in accordance

with an approved engineered design. Pins shall be external, internal or a combination of the two.

Pins shall be ¹ /2-inch-diameter (12.7 mm) steel, ³ /4inch-diameter (19.1 mm) wood or ¹ /2-inch-diameter (12.7 mm) bamboo.
External pins shall be installed vertically on both sides of the wall at a spacing of not more than 24 inches (610 mm) on center. External pins shall have full lateral bearing on the sill plate and the top plate or roof-bearing element, and shall be tightly tied through the wall to an opposing pin with ties spaced not more than 32 inches (813 mm) apart and not more than 8 inches (203 mm) from each end of the pins.
Internal pins shall be installed vertically within the center third of the bales, at spacing of not more than 24 inches (610 mm) and shall extend from top

TABLE AS105.4 OUT-OF-PLANE RESISTANCE METHODS AND UNRESTRAINED WALL DIMENSION LIMITS

METHOD OF OUT-OF-PLANE LOAD RESISTANCEa	FOR ULTIMATE DESIGN WIND SPEEDS (mph)	FOR SEISMIC DESIGN CATEGORIES	UNRESTRAINED WALL DIMENSIONS, Hb		MESH STAPLE SPACING AT BOUNDARY RESTRAINTS
METHOD OF OUT-OF-PLANE LOAD RESISTANCEa	FOR ULTIMATE DESIGN WIND SPEEDS (mph)	FOR SEISMIC DESIGN CATEGORIES	Absolute limit in feet	Limit based on bale thickness _T_c in feet (mm)	Limit based on bale thickness _T_c in feet (mm)
Nonplaster finish or unreinforced plaster	≤ 130	A, B, C, D0	H ≤ 8	H ≤ 5_T_	None required
Pins per Section AS105.4.2	≤ 130	A, B, C, D0	H ≤ 12	H ≤ 8_T_	None required
Pins per Section AS105.4.2	≤ 140	A, B, C, D0, D1, D2	H ≤ 10	H ≤ 7_T_	None required
Reinforcedd clay plaster	≤ 140	A, B, C, D0, D1, D2	H ≤ 10	H ≤ 8_T_0.5 (H ≤ 140_T_0.5)	≤ 6 inches
Reinforcedd clay plaster	≤ 140	A, B, C, D0, D1, D2	10 <H ≤ 12	H ≤ 8_T_0.5 (H ≤ 140_T_0.5)	≤ 4 inchese
Reinforcedd cement, cement-lime, lime or soil-cement plaster	≤ 140	A, B, C, D0, D1, D2	H ≤ 10	H ≤ 9_T_0.5 (H ≤ 157_T_0.5)	≤ 6 inches
Reinforcedd cement, cement-lime, lime or soil-cement plaster	≤ 155	A, B, C, D0, D1, D2	H ≤ 12	H ≤ 9_T_0.5 (H ≤ 157_T_0.5)	≤ 4 inchese
2×6 load-bearing wood studsf at max. 6′ o.c.	≤ 140	A, B, C, D0, D1, D2	_H_g ≤ 9	NA	None required
2×6 load-bearing wood studsf at max. 4′ o.c.	≤ 140	A, B, C, D0, D1, D2	_H_g ≤ 10	NA	None required
2×6 load-bearing wood studsf at max. 2′ o.c.	≤ 140	A, B, C, D0, D1, D2	_H_g ≤ 12	NA	None required
2×4 load-bearing wood studsf at max. 2′ o.c.	≤ 140	A, B, C, D0, D1, D2	_H_g ≤ 10	NA	None required
2×6 nonload-bearing wood studsf at max. 6′ o.c.	≤ 140	A, B, C, D0, D1, D2	_H_g ≤ 12	NA	None required

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 mile per hour = 0.447 m/s. NA = Not Applicable. a. Finishes applied to both sides of stacked bales. Where different finishes are used on opposite sides of a wall, the more restrictive requirements shall apply. b. H = Stacked bale height in feet (mm) between sill plate and top plate or other approved horizontal restraint, or the horizontal distance in feet (mm) between

approved vertical restraints. For load-bearing walls, H refers to vertical height only. c. T = Bale thickness in feet (mm). d. Plaster reinforcement shall be any mesh allowed in Table AS106.13(1) for the matching plaster type, and with staple spacing in accordance with this table.

Mesh shall be installed in accordance with Section AS106.9. e. Sill plate attachment shall be with ⁵ /8-inch anchor bolts or approved equivalent at not more than 48 inches on center where staple spacing is required to be

≤ 4 inches. f. Bales shall be attached to the studs by an approved method. Horizontal framing and attachment at top and bottom of studs shall be in accordance with Section

R602 or an approved alternative. Table R602.7(1) shall be used to determine the top framing member where load-bearing stud spacing exceeds 24 inches o.c. g. H is vertical height only.

APPENDIX AS-10 2022 CALIFORNIA RESIDENTIAL CODE

APPENDIX AS—STRAWBALE CONSTRUCTION

between bales and supporting concrete or masonry. The bales shall be separated from the vapor retarder by not less than ³ /4 inch (19.1 mm), and that space shall be filled with an insulating material such as wood or rigid insulation, or a material that allows vapor dispersion such as gravel, or other approved insulating or vapor dispersion material. Sill plates shall be installed at this interface in accordance with Section AS105.3. Where bales abut a concrete or masonry wall that retains earth, a Class II vapor retarder shall be provided between such wall and the bales.

AS105.6.6 Separation of bales and earth. Bales shall be separated from earth by not less than 8 inches (203 mm).

AS105.6.7 Separation of exterior plaster and earth. Exterior plaster applied to straw bales shall be located not less than 6 inches (102 mm) above earth or 3 inches (51 mm) above paved areas.

AS105.6.8 Separation of wood and plaster. Where wood framing or wood sheathing occurs at the exterior face of strawbale walls, such wood surfaces shall be separated from exterior plaster with two layers of Grade D paper, No. 15 asphalt felt or other approved material in accordance with Section R703.7.3, extending not less than 1 inch (25 mm) past the edges of the framing member.

Exceptions:

Where the wood is preservative treated or naturally durable and is not greater than 1 ¹ /2 inches (38 mm) in width.
Clay plaster shall not be required to be separated from untreated wood that is not greater than 1 ¹ /2 inches (38 mm) in width.

AS105.6.9 Separation of exterior plaster and founda- tion. Exterior plaster shall be separated from the building foundation with a moisture barrier.

AS105.7 Inspections.¶

The building official shall inspect the following aspects of strawbale construction in accordance with Section R109.1:

Sill plate anchors, as part of and in accordance with Section R109.1.1.
Mesh placement and attachment, where mesh is required by this appendix.
Pins, where required by and in accordance with Section AS105.4.

AS105.8 Voids and stuffing.¶

Voids between bales and between bales and framing members shall not exceed 4 inches (102 mm) in width, and such voids shall be tightly stuffed with flakes, loose straw or straw-clay before application of finish.