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Permit guides

ADU Permits in San Pablo: 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.

Who handles your permit

ADU permits in San Pablo run through the Community Development Department — Building Services, at 1000 Gateway Ave., San Pablo, CA 94806, (510) 215-3030. The city's published target is 15 business days for the first plan-review cycle and 10 working days for each cycle after that — quicker than the state-mandated 60-day ceiling, as long as the application is complete. The clock runs on complete submittals only, so the completeness of your package is what actually controls the timeline.

What you can build

San Pablo's rules were rewritten in Ordinance 2025-005 (§17.60.070) and include a few homeowner-friendly departures from state minimums:

San Pablo doesn't publish a preapproved ADU plan library, so every unit is a custom plan set — which makes completeness the single biggest lever on your timeline.

What San Pablo's 2025 ADU ordinance changed

Ordinance 2025-005 gave homeowners more than the state minimum. Studio and one-bedroom detached units go up to 1,000 sq ft — above the 850-sq-ft baseline many cities inherited from state law — and two-plus bedrooms get the full 1,200. Near transit it's generous too: up to 18 feet within a half-mile of a major transit stop, with two more feet allowed to match the main house's roof pitch. A true two-story ADU (up to 20 feet at the eave, 25 at the peak) is possible with an Administrative Use Permit. The ordinance also restates the state rule that utilities can't force a new separate connection or fee for an ADU unless it's built with a brand-new house — useful if the water or sewer provider quotes new service. The city has also explored technical and financial assistance programs for ADU construction and legalization; ask staff what's currently active.

What goes into the submittal

• Building permit application with site plan, floor plans, roof plan, exterior and interior elevations, foundation/floor framing/roof framing plans with sections and details, HVAC, electrical, plumbing, and a CALGreen mandatory-measures sheet.
• Structural and truss calculations where applicable, plus Title 24 Part 6 energy calculations and forms.
• Stormwater pollution prevention statement and a construction & demolition debris plan — San Pablo's franchise hauler is Richmond Sanitary Service, and only its debris box may be used for C&D waste.
• Owner/builder form if you're doing the work yourself.

Where applications usually get stuck

• Incomplete packages. The submittal list runs to multiple plan sheets plus CALGreen and stormwater documents — one missing sheet stops the published 15-day review clock.
• C&D debris rules catch people. Only Richmond Sanitary Service debris boxes are allowed; receipts are checked before final inspection.
• The studio/1-bed cap of 1,000 sq ft — design past it and you'll be redesigning.
• Detached accessory-structure conversions: max 150 sq ft of expansion for ingress/egress, and side/rear setbacks must be sufficient for fire and safety.
• Unpermitted in-law units. Legalization adds an amnesty checklist and corrective work — and inspectors will want to see inside walls.