Sonoma County New Construction Homes for Sale

By Matthew Martinez, Founder, CEO & Managing Broker, Diamond Real Estate Group. California DRE #01869679.

New construction homes in Sonoma County are mostly found inside the cities, because county policy steers urban growth to city limits and a few unincorporated service areas. Rohnert Park has the county’s clearest set of adopted specific plans, and Santa Rosa is planning its southern corridor. Before you sign a builder’s contract, make sure you have read the Department of Real Estate public report, any Notice of Special Tax, and the builder’s warranty and claim procedures under California’s Right to Repair Act (SB 800).

At a glance

Where to look in Sonoma County

Sonoma County’s General Plan draws Urban Service Areas as the limit of urban development for unincorporated communities, and community separators keep open land between cities such as Petaluma, Rohnert Park and Santa Rosa. In practice, subdivisions with public water and sewer are a city story. Outside those lines, "new construction" usually means a custom home on an existing rural parcel, which is a different process; see our Sonoma County land for sale page.

Rohnert Park. The city’s specific plans page lists the plans that shape most of its newer neighborhoods:

Explore the local guide and property-search options on our Rohnert Park homes for sale page, and see Cotati real estate next door.

Santa Rosa. The city has begun the South Santa Rosa Specific Plan, covering about 1,900 acres along the Santa Rosa Avenue corridor and areas west of US 101, including both city and unincorporated land. The city’s page set an early-2026 completion target and does not show an adoption date, so ask the Planning and Economic Development Department where the plan stands before relying on it. Our Santa Rosa real estate page covers the city’s neighborhoods.

Other cities. Petaluma real estate, Windsor homes for sale, Healdsburg real estate, Sonoma real estate and Cloverdale homes for sale each run their own planning departments and approve their own subdivisions and townhome projects. We did not verify a current project list for these cities; the planning department’s current-projects page or counter is the reliable source. If transit matters, our guide to homes near SMART and the ferry shows which cities have stations.

What to check before you buy

The DRE public report. Under Business and Professions Code 11018.1, the subdivider must give you a copy of the Real Estate Commissioner’s public report before you sign a binding contract, and take a receipt. A copy must be posted at the sales office. The Department of Real Estate describes the report as covering the CC&Rs that govern use of the property and the costs of the homeowners association and common areas. For a condo or townhome project, the statute also requires a general information statement about owners’ associations. Read both alongside our HOA documents guide.

Special taxes (Mello-Roos) and assessments. If a lot is in a community facilities district, Government Code 53341.5 requires the subdivider to give you a signed "Notice of Special Tax" before you sign a purchase contract or deposit receipt. You may cancel by written notice within three days of in-person delivery or five days after it is mailed. The notice covers the maximum tax and what it funds. Our Mello-Roos guide explains how to read it. Sanitation zones, water districts and fire districts can also add lines to the tax bill.

Supplemental tax bill. The Sonoma County Assessor issues supplemental assessments after a change in ownership or completed new construction, billing the difference between the prior and new assessed value. An event from June 1 to December 31 produces one bill; an event from January 1 to May 31 produces two. Appeals go to the Assessment Appeals Board within 60 days of the notice. On a new home, the lot may have been assessed as vacant land, so the change can be large. Budget for it with our supplemental tax bill guide.

Your own inspection. A brand-new home still benefits from an independent inspection, ideally before drywall and again before the final walkthrough. Builder contracts set the access rules, so ask before you sign. Our home inspection guide explains what an inspector covers.

Builder warranties and SB 800 in plain terms

California’s Right to Repair Act (Civil Code 895–945.5, beginning at section 895) sets building standards for new homes, starting at section 896, and a claims process that runs before any lawsuit.

• Fit and finish. Under Civil Code 900, the builder must give a written limited warranty of at least one year covering cabinets, mirrors, flooring, interior and exterior walls, countertops, paint and trim. If no warranty is given, the period is one year by default.
• Documents. Under Civil Code 912, the builder must give you maintenance recommendations, product warranties and its own limited warranties at the sale. Within 30 days of a written request, it must also provide relevant plans, soils reports and engineering calculations for structural, fire safety or soils claims. The builder must name an agent or third party to receive claims, show that contact in the sales documents, and record a notice of the procedures on title.
• Making a claim. Civil Code 910 requires written notice describing the problem in reasonable detail, sent by certified mail, overnight mail or personal delivery. A customer-service request alone does not count as that notice. The builder must acknowledge it in writing within 14 days (Civil Code 913).
• Time limit. Claims under the Act generally must be brought within 10 years of substantial completion (Civil Code 941).

A builder’s warranty is different from a home warranty plan you buy separately; our home warranty guide explains the difference.

Having your own agent at a builder’s sales office

The sales staff in a model home represent the builder. Bringing your own agent gives you someone on your side to compare lot premiums, special tax lines and HOA dues across communities, and to read the builder’s purchase agreement, which is usually the builder’s own form rather than a standard one. Many builders have agent-registration rules, and some require your agent to come to the first visit, so ask about the policy before you tour. Our step-by-step guide to buying new construction in California walks through the contract, deposits and closing timeline, and our Sonoma County buyer guide covers financing and offers.

Questions people ask

Where are new subdivisions in Sonoma County?

Mostly inside city limits. Rohnert Park’s University District and Southeast specific plans are the best documented on a city website. Santa Rosa is preparing its South Santa Rosa Specific Plan. Other cities approve projects one at a time through their planning departments.

Do new homes in Sonoma County have Mello-Roos taxes?

Some do. If a lot is in a community facilities district, the builder must give you a signed Notice of Special Tax before you sign. Read every line of the tax bill and the notice.

Can I build a new house outside the cities?

Often yes, on an existing legal parcel, under county zoning, well, septic and fire-safe rules. That is a custom build, not a subdivision purchase. See our land page.

What warranty comes with a new home in California?

At least a one-year written fit-and-finish warranty under Civil Code 900, plus the Right to Repair Act’s building standards. Claims under the Act generally run up to 10 years from substantial completion.

Do I need an inspection on a brand-new home?

It is a good idea. City building inspections check code compliance, not workmanship or finish quality. A private inspector before drywall and before closing can catch items for the builder’s punch list.

Will I get a supplemental tax bill?

Usually. A change in ownership triggers a supplemental assessment, and the Sonoma County Assessor bills the difference in value. The State Board of Equalization notes that lenders do not receive supplemental bills, even with an impound account, so plan to pay it yourself.

Can I use my own agent with a builder?

Yes. Ask the sales office about its agent-registration policy before your first visit, since some builders require the agent to be present or registered from the start.

Sources & notes

1. Sonoma County GIS: Urban Service Areas dataset description.
2. Sonoma LAFCO: Community separators policy.
3. City of Rohnert Park: Specific plans.
4. City of Santa Rosa: South Santa Rosa Specific Plan.
5. California Department of Real Estate: Public reports.
6. Business and Professions Code 11018.1.
7. Government Code 53341.5.
8. Civil Code 900, 910, 912, 913 and 941 (Right to Repair Act).
9. Sonoma County Assessor: Supplemental notices.
10. State Board of Equalization: Supplemental assessment.

Notes: Unit counts and plan status come from city pages at the time of review; plans are amended often, and a plan’s unit cap is not a forecast of what will be built. We did not verify current project lists for Petaluma, Windsor, Healdsburg, Sonoma or Cloverdale. Statute text was reviewed through public mirrors; confirm on leginfo. Rules change; verify before you buy.

General information, not legal, tax or lending advice. Updated November 2026. Primary sources are linked in this guide.

Related: Sonoma County homes for sale · Where to live in Sonoma County · Buying new construction in California · Mello-Roos in California · Supplemental tax bills