Permits & Code
Factory-built housing (HCD)
Homes built in a factory to California codes go through HCD's Factory-Built Housing program: approved plans, an HCD insignia before shipment, and local inspection of the installation.
How it works
- Plans. The manufacturer's plans are reviewed and approved by an HCD-approved Design Approval Agency.
- Inspection and insignia. An HCD-approved Quality Assurance Agency inspects production, and the HCD insignia is applied before the unit leaves the factory.
- Installation. The local building department permits and inspects the foundation, utility connections and installation.
Hemp-lime in a factory
Factory-built units still have to meet the California Residential Code, so hemp-lime walls would follow Appendix BL or an approved alternative design. Cast hempcrete takes weeks to dry, so precast blocks or engineered panels suit factory work better. No HCD-approved hemp-lime factory system was found in MicroHom's research.
Not covered
Tiny homes on wheels are generally recreational vehicles or park trailers under HCD Information Bulletin 2016-01, not factory-built housing.
Sources
- HCD Factory-Built Housing, insignia. Checked Oct 17, 2026.
- HCD Factory-Built Housing, approved third-party agencies. Checked Oct 17, 2026.
- HCD Information Bulletin 2016-01, tiny homes. Checked Oct 17, 2026.
- 2025 CRC Appendix BL, Section BL103 Hemp-Lime Construction (gocodebook; effective Jan 1, 2026). Checked Oct 17, 2026.
Last updated Oct 18, 2026. Each source above was checked on the date shown.