Commercial Real Estate in Sonoma County: Buying and Leasing Guide
Buying or leasing commercial property in Sonoma County starts with one question: is the parcel inside one of the county’s nine cities, or in unincorporated territory regulated by Permit Sonoma? The answer decides the zoning code, the permit counter and the transfer tax. Every sale pays the county documentary transfer tax of $1.10 per $1,000 of value, and sales inside Santa Rosa and Petaluma also pay a city tax of $2.00 per $1,000.
This guide is for business owners looking for space and investors weighing a building in Santa Rosa, Petaluma or elsewhere in the county. It covers jurisdiction, the main commercial and industrial zones, Santa Rosa’s downtown plan, cannabis as a land-use matter, transfer tax and the local due diligence items that tend to decide a deal. For the general process of buying, leasing and investing, see our commercial real estate hub.
City or county: who regulates the parcel
Sonoma County’s nine incorporated cities are Santa Rosa, Petaluma, Rohnert Park, Cotati, Sebastopol, Healdsburg, Windsor, Sonoma and Cloverdale. Each has its own zoning code, planning department and building division. Outside those boundaries, Permit Sonoma, the county’s planning and permitting agency, applies the county zoning code.
Mailing addresses don’t settle the question. A “Santa Rosa” or “Petaluma” address can sit outside city limits, and county commercial zoning works differently from city zoning. Before you write an offer, look the parcel up on the county’s records and confirm the zoning with the agency that controls it, in writing if the use matters to your business.
Our Sonoma County guide describes the cities and unincorporated areas; our Santa Rosa and Petaluma pages cover the two largest cities.
Commercial and industrial zones in unincorporated Sonoma County
Permit Sonoma’s zoning page groups the county’s commercial districts in Article 10 of the zoning code and most industrial districts in Article 12. The district names give a good sense of the intended use, but the allowed-use tables and any combining districts control.
| Code | District | Group |
|---|---|---|
| CO | Administrative and Professional Office | Commercial |
| C1 | Neighborhood Commercial | Commercial |
| LC | Limited Commercial | Commercial |
| C2 | Retail Business and Service | Commercial |
| C3 | General Commercial | Commercial |
| K | Recreation and Visitor-Serving Commercial | Commercial |
| CR | Commercial Rural | Commercial |
| AS | Agricultural Services | Commercial |
| MP | Industrial Park | Industrial |
| M1 | Limited Urban Industrial | Industrial |
| M2 | Heavy Industrial | Industrial |
| M3 | Limited Rural Industrial | Industrial |
Combining districts can add a second layer. Examples on Permit Sonoma’s list include the Historic (HD), Scenic Resources (SR), Floodway (F1), Floodplain (F2) and Geologic Hazard Area (G) districts, each with its own article and standards. A rural commercial parcel may also depend on a well and septic system, which limits what the site can support.
Wineries, tasting rooms and other agricultural businesses mostly sit on agricultural zoning rather than commercial zoning. Our guides to Sonoma County agricultural zoning and tasting room space cover those properties.
Santa Rosa: districts and the downtown plan
Santa Rosa is the county seat and the county’s largest commercial market. Chapter 20-23 of its zoning code, as amended through 2025, sets out these commercial districts:
- Commercial: CO (Office Commercial), CN (Neighborhood Commercial), CG (General Commercial), CSC (Community Shopping Center) and CV (Motor Vehicle Sales).
- Mixed use: CMU (Core Mixed Use), SMU (Station Mixed Use), MMU (Maker Mixed Use), NMU (Neighborhood Mixed Use) and TV-M (Transit Village-Mixed).
Chapter 20-24 adds three industrial and business park districts: BP (Business Park), IL (Light Industrial) and IG (General Industrial). Each chapter’s use table, not the district name, decides whether a particular business is allowed.
In October 2020 the City Council adopted the updated Downtown Station Area Specific Plan, replacing the 2007 plan. It covers Courthouse Square, Railroad Square and the surrounding blocks, anchored by the SMART station and the Downtown Transit Mall. The plan’s goals include more housing downtown, more commercial activity and removing barriers to development.
The city offers a floor area ratio bonus in the plan area for projects that include affordable housing units or a childcare facility. For a buyer looking at a downtown building or a redevelopment site, that bonus and the plan’s land use map are the starting point for a feasibility check. Mixed-use buildings are common in older downtowns; our page on mixed-use buildings covers financing and code questions.
Cannabis: a land-use question first
Commercial cannabis is legal in California under state licensing, but each city and the county decide where it can operate. Treat it as a zoning question before anything else, and confirm the current rules with the jurisdiction: ordinances in this area have been amended often.
Santa Rosa’s comprehensive cannabis ordinance, adopted December 19, 2017, is the version summarized here; we have not traced later amendments, so check the current zoning code before relying on it. As adopted, it placed testing laboratories, non-volatile manufacturing and distribution in the Business Park and industrial districts. A minor use permit was required where those uses abut residential property. Dispensaries needed a conditional use permit and had to be at least 600 feet from a K-12 school and from another permitted dispensary. Unincorporated Sonoma County regulates cannabis separately through Permit Sonoma.
For a landlord or buyer, a cannabis tenant also raises lender, insurance and lease questions that go beyond zoning. Get those answered before you sign.
Transfer tax on a Sonoma County commercial sale
The county tax is $0.55 per $500 of value, the same as $1.10 per $1,000, and the county reduces it by any loans the buyer assumes. Santa Rosa and Petaluma each add $2.00 per $1,000, with no reduction for assumed loans.
| Where the property is | County tax | City tax | Total on a $3,000,000 sale |
|---|---|---|---|
| Santa Rosa | $1.10 per $1,000 | $2.00 per $1,000 | $9,300 |
| Petaluma | $1.10 per $1,000 | $2.00 per $1,000 | $9,300 |
| Cloverdale, Cotati, Healdsburg, Rohnert Park, Sebastopol, Sonoma, Windsor | $1.10 per $1,000 | None listed by the county | $3,300 |
| Unincorporated county | $1.10 per $1,000 | Not applicable | $3,300 |
The totals are simple illustrations with no assumed loans. Local custom in Diamond’s North Bay markets is for the seller to pay the transfer tax, though that is negotiable and custom varies; commercial buyers and sellers often address it directly in the purchase agreement. Our California transfer tax guide explains exemptions and how the tax is figured.
Due diligence that matters locally
The standard commercial checklist applies here: title, survey, leases, financials, physical inspections and environmental review. Our commercial due diligence checklist walks through it. In Sonoma County, a few items deserve early attention.
- Confirm the use in writing. Ask the city or Permit Sonoma whether your intended use is permitted by right, needs a use permit, or isn’t allowed, and whether the existing use has a valid permit.
- Check utility capacity and fees. A change of use, such as office to food service, can trigger sewer and water connection or capacity charges; ask the city utility or sanitation district for an estimate.
- Look up the hazard maps. Check FEMA flood maps along the Petaluma River, Santa Rosa Creek and the Russian River corridor, and the state’s fire hazard maps for parcels at the wildland edge.
- Review accessibility. California requires commercial landlords to state in the lease whether a Certified Access Specialist has inspected the property; see our CASp and ADA guide.
- Plan for property tax. A purchase is generally a change in ownership under Proposition 13, so budget for reassessment to the purchase price rather than the seller’s current bill.
- Read rural systems closely. On unincorporated commercial land, well yield, septic capacity and fire flow can limit occupancy and expansion.
Diamond may refer you to partners we work with; you’re free to choose any provider.
Leasing, buying for your business, or investing
Business owners usually compare a lease against buying a building for their own use. Our guides to owner-user commercial property and commercial lease types lay out the trade-offs, and our page on industrial and warehouse space covers the flex and light-industrial buildings common along the Highway 101 corridor.
Owners preparing to sell should read our page on selling commercial property, which covers pricing, tenant estoppels and tax planning at sale.
Questions people ask
What is the transfer tax on commercial property in Santa Rosa?
The county charges $1.10 per $1,000 of value, reduced by assumed loans, and Santa Rosa adds $2.00 per $1,000 with no reduction for assumed loans. Together that is $3.10 per $1,000 when no loan is assumed.
Does Petaluma have a city transfer tax?
Yes. The Sonoma County Recorder lists Petaluma’s city tax at $2.00 per $1,000, collected along with the county tax.
Who handles zoning for commercial property outside city limits?
Permit Sonoma, the county’s planning and permitting agency, applies the county zoning code to unincorporated parcels.
What zones allow industrial uses in unincorporated Sonoma County?
The county’s industrial districts are MP (Industrial Park), M1 (Limited Urban Industrial), M2 (Heavy Industrial) and M3 (Limited Rural Industrial). Check the allowed-use table for your specific use.
Can I open a cannabis business in any commercial building?
No. Each city and the county decide where cannabis businesses may operate, and the rules vary by use type. Santa Rosa’s 2017 ordinance, for example, kept testing, manufacturing and distribution in business park and industrial districts and spaced dispensaries away from schools.
Is there an incentive for building downtown in Santa Rosa?
The Downtown Station Area Specific Plan offers a floor area ratio bonus for projects that include affordable housing units or a childcare facility. Ask the city about any other current fee programs.
Will my property taxes go up when I buy a commercial building?
Usually. A purchase is generally a change in ownership, so the county assessor reassesses the property to its value at the time of sale.
Can Diamond help with both leasing and sales?
Yes. Diamond handles commercial sales and leasing in Sonoma County and across our North Bay markets.
If you are looking for space or considering a commercial purchase in Sonoma County, tell us the use, size and timing you have in mind. Contact us to start a focused search or to discuss selling or leasing a building.
This guide is general information, not legal or tax advice. Zoning, use permits and reassessment can change the value of a commercial deal, so have a California real estate attorney and a tax adviser review your lease or purchase contract before you sign.
Sources & notes
- County of Sonoma Clerk-Recorder: Documentary Transfer Tax
- Permit Sonoma: County zoning districts
- City of Santa Rosa: Downtown Station Area Specific Plan
- City of Santa Rosa: Ordinance ORD-2017-025, comprehensive cannabis regulations (December 19, 2017)
- Santa Rosa Zoning Code Chapter 20-23, Commercial Zoning Districts (GoCodebook mirror of the code text, as of Sept. 25, 2026)
- Santa Rosa Zoning Code Chapter 20-24, Industrial Zoning Districts (GoCodebook mirror of the code text, as of Sept. 25, 2026)
- Note: cannabis rules are described as adopted in December 2017; the city may have amended them since, so confirm with Santa Rosa Planning.
Last reviewed October 2026 by Matthew Martinez.
