Permits & Code
Permits and code
The California rules a small hemp home has to meet, in the order a project usually meets them: land use, building code, energy code, factory rules if prefabricated, then the county.
The usual order
- Land use. Is the home allowed on the parcel? For a backyard unit, state ADU law sets objective standards local rules must allow.
- Building code. The 2025 California Residential Code. Hemp-lime walls follow Appendix BL where the jurisdiction has adopted it, or the alternative-materials process (R104.11) where it has not.
- Energy code. Title 24 Part 6 sets wall, window and solar requirements by climate zone.
- Factory-built rules, if the home is built off site: HCD plan approval and insignia, then local inspection of installation.
- County and city. Local zoning, fees and inspections.
MicroHom summarises published rules. It is not legal or engineering advice, and the local building official decides what is approved.
In this section
- Hemp-lime appendix (BL)What Appendix BL allows and requires.
- ADUs and tiny homesState ADU law and tiny homes on wheels.
- Factory-built housing (HCD)Plan approval, insignia and installation for prefab homes.
- Energy code (Title 24)Mass walls, windows and solar for small homes.
- County profilesSourced county housing figures.
Sources
- 2025 California Residential Code, Appendix BL, Section BL101 General (gocodebook). Checked Oct 17, 2026.
- 2025 CRC Section R104, duties and powers of the building official (alternative materials, R104.11). Checked Oct 17, 2026.
- HCD, Accessory Dwelling Unit Handbook (March 2026 update). Checked Oct 18, 2026.
- HCD Factory-Built Housing, insignia. Checked Oct 17, 2026.
- California Energy Commission, 2025 Single-Family Residential Compliance Manual. Checked Oct 17, 2026.
- FEMA P-2192 Seismic Design Category maps for the 2024 IRC (July 2024). Checked Oct 17, 2026.
Last updated Oct 18, 2026. Each source above was checked on the date shown.