Unpermitted ADUs create real risk at sale, refinancing, and with insurance. We manage the complete legalization process — as-built documentation, city permits, required corrections, and final inspection. Detailed written quotes. No surprises.
An unpermitted ADU is any residential structure — converted garage, backyard guest house, basement apartment, or detached unit — that was built or converted without obtaining the required city building permits. It may be a quality structure that's been occupied for years, but without permits it carries significant legal and financial risk.
The Chino Valley has a notable stock of older informal structures, particularly in Chino's established neighborhoods. San Bernardino County and both city jurisdictions have clear pathways for legalization under California's ADU mandate.
Three situations make unpermitted ADUs a serious problem:
Legalizing proactively — not under deadline pressure — gives you control over the process and typically produces the best cost outcome.
Here's exactly how we handle unpermitted ADU legalization in Chino:
First step: determine whether the property is in City of Chino or City of Chino Hills — each has its own retroactive permit process.
Inspect and document existing structure condition across all systems.
Architect prepares as-built documentation for the applicable city's retroactive permit application.
For Chino Hills, we check VHFHSZ status — fire-resistant exterior requirements may apply to legalization projects.
Submit application, complete required corrections — typically egress, electrical, weatherization.
City sign-off. Legal ADU in the correct jurisdiction. Certificate of Occupancy issued.
The most common code gaps we find in Chino unpermitted ADUs:
We identify every gap during the initial assessment and include all correction costs in our detailed written legalization quote.