← PCG Engineering
Permit guides
ADU Permits in Sacramento: a Homeowner's Guide
What you can build, which permits you need, and how the review actually works — in plain language.
Last updated October 2026. Rules change; always confirm current requirements with the city or county before you build.
First: city or county?
Sacramento is two separate jurisdictions. If your property is inside city limits, you deal with the City of Sacramento Community Development Department. If you're in an unincorporated area, it's Sacramento County's Building Permits & Inspection Division. They have separate portals, separate plan libraries, and separate reviewers. The state rules below apply to both, but the submission path is different — using the wrong one is one of the most common ways applications stall.
What you can build
California state law sets the baseline, and Sacramento follows it:
1,200 sq ftMax for a detached ADU
50% / 1,200Max for an attached ADU (50% of the main home, up to 1,200 sq ft)
500 sq ftMax for a Junior ADU, carved from existing space
16 ftHeight limit for most detached ADUs (18 ft near major transit or above a garage)
4 ftMinimum rear and side setbacks for detached ADUs
1 + 1One ADU plus one JADU allowed per single-family lot
There is no minimum lot size for an ADU under state law. Converted garages and other existing structures keep their current footprint — no new setbacks apply to the conversion itself.
Two paths to a permit
1. Pre-approved plans. Both the city and the county publish libraries of pre-reviewed ADU designs. These have already cleared structural plan check, so review focuses on your specific site: placement, setbacks, utilities, drainage. This is usually the fastest route.
2. Custom plans. An architect or designer draws a unit for your lot. More flexible, but every sheet goes through full plan check — expect about 30 days for a standard review round, plus correction cycles.
Pre-approved doesn't mean permit-free. You still need a building permit, and reviewers still verify site placement, foundation conditions, utility connections, and fire access for your specific property.
The process, step by step
- Confirm the lot. Verify zoning, setbacks, easements, and whether the property has any historic designation. Sacramento offers an optional low-cost zoning check before you invest in full plans — worth it if anything about the site is ambiguous.
- Prepare the plan set. Typically: site plan, floor plans, exterior elevations, foundation and framing details, structural calculations, Title 24 energy compliance, electrical/plumbing/mechanical layouts, and utility connection plans.
- Submit through the portal. The application is filed online with the city or county. Under state law, the jurisdiction must act within 60 days — but the clock starts only once the application is deemed complete.
- Plan check and corrections. Reviewers return comments ("corrections"). Each round adds weeks. Complete, coordinated submittals are what separate a two-month review from a six-month one.
- Pay fees, pull the permit. Permit, plan-review, trade, and state surcharge fees are due at issuance. Don't start work before the permit is issued.
- Build and inspect. Required inspections run from foundation through framing, MEP rough-ins, insulation, to final. Final sign-off is what makes the unit a lawful ADU.
Where applications usually get stuck
- Incomplete submittals. Missing structural details or energy forms are the top reason the 60-day clock never starts.
- Site plan problems. Wrong setbacks, unmarked easements, unclear utility connections.
- Garage conversions. Changing a garage to living space triggers requirements for foundation, ceiling height, insulation, egress windows, and fire separation — it's never just "add drywall."
- Unpermitted existing work. If there's already an unpermitted unit, legalization (including AB 2533 provisions) adds an amnesty checklist and corrective work to the package — and inspectors will want to see inside walls.
Not sure where to start? That's the part we do. We look at your property, map the requirements, coordinate the plans and specialists, and manage the submittal and corrections — one point of contact.