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).
- Wall height: in accordance with Table AS105.4.
- Braced wall panel length, and increase in Seismic Design Categories C, D0, D1 and D2: the required length of bracing for buildings using strawbale nonstructural walls shall comply with Section R602.10.3 of this code, with the additional requirements that Table R602.10.3(3) shall be applicable to buildings in Seismic Design Category C, and that the minimum total length of braced wall panels in Table R602.10.3(3) shall be increased by 60 percent.
OUT-OF-PLANE RESISTANCE AND UNRESTRAINED WALL DIMENSIONS
|METHOD OF OUT-OF-PLANE RESISTANCEa||FOR WIND DESIGN SPEEDS (mph)||FOR SEISMIC DESIGN CATEGORIES||UNRESTRAINED WALL DIMENSIONS, Hb||MESH STAPLE SPACING AT BOUNDARY RESTRAINTS|
|Absolute limit in feet||Limit based on bale thickness Tc in feet (mm)|
|Nonplaster finish or unreinforced plaster||≤ 100||A, B, C, D0||H ≤ 8||H ≤ 5T||None required|
|Pins per Section AS105.4.2||≤ 100||A, B, C, D0||H ≤ 12||H ≤ 8T||None required|
|Pins per Section AS105.4.2||≤ 110||A, B, C, D0, D1, D2||H ≤ 10||H ≤ 7T||None required|
|Reinforcedc clay plaster||≤ 110||A, B, C, D0, D1, D2||H ≤ 10||H ≤ 8T0.5 (H ≤ 140T0.5)||≤ 6 inches|
|Reinforcedc clay plaster||≤ 110||A, B, C, D0, D1, D2||10 < H ≤ 12||H ≤ 8T0.5 (H ≤ 140T0.5)||≤ 4 inchese|
|Reinforcedc cement, cement-lime, lime or soil-cement plaster||≤ 110||A, B, C, D0, D1, D2||H ≤ 10||H ≤ 9T0.5 (H ≤ 157T0.5)||≤ 6 inches|
|Reinforcedc cement, cement-lime, lime or soil-cement plaster||≤ 120||A, B, C, D0, D1, D2||H ≤ 12||H ≤ 9T0.5 (H ≤ 157T0.5)||≤ 4 inchese|
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
- 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.
- 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.
- T = Bale thickness in feet (mm).
- Plaster reinforcement shall be any mesh allowed in Table AS106.16 for the matching plaster type, and with staple spacing in accordance with this table. Mesh shall be installed in accordance with Section AS106.9.
- 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.
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, 3/4-inch-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 course to bottom course. The bottom course shall be similarly connected to its support and the top course shall be similarly connected to the roof- or floor-bearing member above with pins or other approved means. Internal pins shall be continuous or shall overlap through not less than one bale course.
Where wood framing or wood sheathing occurs on 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.
- Where the wood is preservative treated or naturally durable and is not greater than 11/2 inches (38 mm) in width.
- Clay plaster shall not be required to be separated from untreated wood that is not greater than 11/2 inches (38 mm) in width.