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Permit guides

ADU Permits in Santa Rosa: a Homeowner's Guide

What you can build, which permits you need, and how review actually works — in plain language.

Last updated October 2026. Rules change; always confirm current requirements with the city before you build.

Who handles your permit

The City of Santa Rosa's Planning and Economic Development Department (PED) handles both planning review and building permits. Its permit center is in Room 3 of City Hall at 100 Santa Rosa Avenue, Santa Rosa, CA 95404 — in-person visits are by appointment only. Applications go through the city's Accela Citizen Access portal, and planning staff can be reached at (707) 543-3200. If your property sits in unincorporated Sonoma County rather than city limits, you're with Permit Sonoma instead — a separate agency at 2550 Ventura Avenue with its own portal and reviewers. Using the wrong jurisdiction is one of the most common ways a project stalls before it starts.

What you can build

California state law sets the baseline, and Santa Rosa follows it:

There is no minimum lot size for an ADU under state law. ADUs under 750 square feet are exempt from impact fees, which is the single biggest cost break in the fee schedule.

Pre-approved plans

Santa Rosa offers pre-approved ADU designs, and regional resources add more options: the Napa Sonoma ADU Center maintains standard plans and workbooks, and Permit Sonoma has been coordinating a countywide preapproved plan list under AB 1332. A pre-checked plan skips much of the structural plan check, so review focuses on your site — setbacks, utilities, drainage, fire access. Designers set their own per-use licensing fee; regional programs encouraged keeping it around $1,000.

What goes into the submittal

• Site plan — lot lines, existing structures, setbacks, easements, utility locations, and the proposed ADU footprint.
• Architectural plans — floor plans, elevations, sections, roof plan.
• Structural details and calculations — foundation, framing, shear walls, connections.
• Title 24 energy compliance — required forms and documentation.
• Electrical, plumbing, and mechanical layouts.
• Utility connection plans — water, sewer, and any new or upsized laterals.
• Deed restrictions — required for JADUs.

Where applications usually get stuck

• Overlays. Historic, Hillside, Creekside, Floodplain, and Wildland-Urban Interface overlays can change setbacks, height limits, and review steps — check yours before designing.
• Water and sewer. City water/sewer versus a private well or septic — a new or upsized lateral and capacity fees may apply, and septic brings county health review into the picture.
• The clock never starts. Incomplete submittals — missing structural details or energy forms — mean the application is never deemed complete, and the 60-day deadline doesn't run.
• Denials. If a complete application is denied, the city must give you a written list of deficiencies — and you can appeal in writing to the Planning Commission.