Strawbale walls shall be considered to be nonrated, except for walls constructed in accordance with Section AS107.1.1 or AS107.1.2. Alternately, fire-resistance ratings of strawbale walls shall be determined in accordance with Section R302 of the California Residential Code.
One-hour fire-resistance-rated nonload-bearing clay plastered strawbale walls shall comply with all of the following:
- Bales shall be laid flat or on-edge in a running bond.
- Bales shall maintain thickness of not less than 18 inches (457 mm).
- Gaps shall be stuffed with straw-clay.
- Clay plaster on each side of the wall shall be not less than 1 inch (25 mm) thick and shall be composed of a mixture of 3 parts clay, 2 parts chopped straw and 6 parts sand, or an alternative approved clay plaster.
- Plaster application shall be in accordance with Section AS104.4.3.3 for the number and thickness of coats.
Two-hour fire-resistance-rated nonload-bearing cement plastered strawbale walls shall comply with all of the following:
- Bales shall be laid flat or on-edge in a running bond.
- Bales shall maintain a thickness of not less than 14 inches (356 mm).
- Gaps shall be stuffed with straw-clay.
- 11/2-inch (38 mm) by 17-gage galvanized woven wire mesh shall be attached to wood members with 11/2-inch (38 mm) staples at 6 inches (152 mm) on center. 9 gage U-pins with not less than 8-inch (203 mm) legs shall be installed at 18 inches (457 mm) on center to fasten the mesh to the bales.
- Cement plaster on each side of the wall shall be not less than 1 inch (25 mm) thick.
- Plaster application shall be in accordance with Section AS104.4.8 for the number and thickness of coats.