Permit guides

ADU Permits in Rohnert Park: 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

ADUs in Rohnert Park run through the Development Services Department: the Planning Division at (707) 588-2231 (planning@rpcity.org) and the Building Division at (707) 588-2240 (building@rpcity.org), at 130 Avram Avenue, Rohnert Park, CA 94928. Plans can be submitted in person (three sets of drawings) or electronically as PDFs, and anything involving fire is automatically routed to the Fire Services Division. If you're in unincorporated Sonoma County, you're with Permit Sonoma instead — a separate agency.

What you can build

California state law sets the baseline, and Rohnert Park 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

4 ftMinimum rear and side setbacks for detached ADUs

29 daysTypical turnaround for an initial review; resubmittals take about 20

There is no minimum lot size for an ADU under state law. Multifamily properties have their own rules — including a two-ADU allowance on conversions of existing accessory structures — so check the city's ADU handbook for your property type.

Pre-approved plans

Rohnert Park doesn't publish its own pre-approved ADU plan library. Under AB 1332 the city maintains a list of preapproved and repeatable plans — check with staff for what's currently posted. What the city does publish is unusually thorough: a step-by-step ADU handbook plus an application checklist (revised October 2024) that spells out every sheet, note, and detail the plan set must include. Follow it literally — it's the reviewer's own grading rubric.

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.

What goes into the submittal

Site plan — lot lines, setbacks, easements, existing structures, vicinity map, and lot coverage calculations.
Architectural plans — floor plans, elevations, sections, materials and colors — drawn to scale (1/4" = 1' minimum) with bar scale and north arrow.
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 and sewer, including any lateral upgrades.
Stormwater determination worksheet and preliminary title report.
Deed restriction — prohibiting separate sale and short-term rentals.

Where applications usually get stuck

The deed restriction. Every ADU requires a recorded deed restriction prohibiting separate sale — and short-term rentals are off the table.
Compatibility. Exterior design must be architecturally compatible with the primary home — and second-story ADUs face privacy requirements and a 16-foot height cap.
Outside review. The city may send plans to an independent plan review firm at your cost, billed hourly — budget for it.
Water service. A new or upsized water lateral may be required to meet minimum service levels — check early, not at corrections.
Incompleteness. The 29-day turnaround only applies to a submittal that meets the checklist; missing sheets restart the clock.

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.

Tell us what you need help with.

Not sure where to start? That's what we're here for.

Send your project

Erik — (916) 540-8960 · Vall — (916) 956-8106
office@pcg-engineering.pro