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Earlier editions: 20222019

Appendix BJ — STRAWBALE CONSTRUCTION

BJ108 Thermal Insulation — 2025 California Residential Code

California Residential Code (Title 24, Part 2.5) · 2025 edition · updated 2026-10-19 · California

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Italicized text is a California amendment to the model code, as printed in the official publication.

Cite as: 2025 California Residential Code (Title 24, Part 2.5) § BJ108 · Effective January 1, 2026 · Official source: Building Standards Commission

BJ108.1 R-value.

The unit R-value of a strawbale wall with bales laid flat is R-1.55 for each inch of bale thickness. The unit R-value of a strawbale wall with bales on-edge is R-1.85 for each inch of bale thickness.

Exceptions & meaning →

BJ108.2 Compliance with Section R302.10.1.

Straw bales meet the requirements for insulation materials in Section R302.10.1 for flame spread index and smoke-developed index as tested in accordance with ASTM E84.

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▸Contents — California Residential Code (Title 24, Part 2.5)
California Residential Code (Title 24, Part 2.5)

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