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Sebastopol Becomes First City in Sonoma County to Allow ADUs to Be Sold Separately
Sebastopol has officially become the first city in Sonoma County to approve the sale of accessory dwelling units as separate homes, marking a major shift in how ADUs can be used across the region.
Following a 4–1 vote by the Sebastopol City Council, the city adopted a new ordinance implementing California Assembly Bill 1033, a 2024 state law that gives local governments the option to allow ADUs to be sold independently as condominiums. Until now, ADUs in California were almost exclusively limited to rental use.
This decision positions Sebastopol at the forefront of a new housing model that could significantly impact homeowners, builders, and first time buyers throughout Sonoma County.
What Changed and Why It Matters
For years, homeowners could build ADUs to house family members or generate rental income, but they could not sell those units separately from the main residence. Assembly Bill 1033 changed that by allowing cities to opt in and permit ADUs to be sold as individual condominium units.
Sebastopol is now one of the first cities in California, and the first in Sonoma County, to take that step.
City leaders and housing advocates supported the ordinance as a way to expand housing supply in a city where the median home price is roughly $1.4 million. By allowing smaller, already built homes to be sold independently, Sebastopol aims to create more attainable homeownership opportunities without large scale new developments.
What the New Sebastopol Ordinance Allows
Under the updated city code, property owners in Sebastopol may now:
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Build a new ADU and sell it separately from the primary home
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Sell an existing ADU as its own condominium unit
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Create two legally separate homes on a single residential property
The ordinance applies to residentially zoned areas across the city and follows the same general framework used for condominiums.
This is not a casual or automatic process. Selling an ADU requires meeting specific legal, planning, and infrastructure requirements.
Key Requirements to Sell an ADU in Sebastopol
Homeowners considering selling an ADU separately should understand that this process is more complex than renting an ADU.
Common requirements include:
Condominium creation
The ADU and primary home must be legally established as condominiums, following California condominium laws. This includes defining ownership boundaries and shared responsibilities.
City application and fees
Owners must apply through Sebastopol’s planning department and pay applicable fees, generally ranging from a few hundred to over a thousand dollars depending on the project.
Separate utilities
Each unit must have its own water, sewer, gas, and electric service. This is a major planning consideration for both new and existing ADUs.
Shared space agreements
If the units share elements such as a driveway, roof, or access path, the owner must create a formal agreement to manage maintenance and costs. In most cases, this takes the form of a small homeowners association.
Lender approval
If there is a mortgage on the property, the lender must consent to the condominium setup. This is one of the most important steps and can influence financing or refinancing decisions.
Once approved, the ADU receives its own property tax bill and is treated as a separate residential unit.
Why Sonoma County Homeowners Are Paying Attention
Sebastopol’s decision is being closely watched across Sonoma County. Cities like Santa Rosa, Petaluma, and Healdsburg now have a real world example of how AB 1033 can be implemented locally.
Housing advocates believe this approach can:
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Increase housing inventory without major new developments
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Create smaller, more affordable homes for first time buyers
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Give homeowners more flexibility in how they use and exit ADU investments
If other Sonoma County cities follow Sebastopol’s lead, sellable ADUs could become a meaningful part of the local housing market over the next several years.
What This Means for IMKAT Homes Clients
For homeowners building ADUs with IMKAT Homes, this announcement changes how projects can be planned from the start.
In cities that adopt similar ordinances, ADUs are no longer limited to rental or family use. They can be designed as future saleable assets. That affects decisions around layout, utilities, access points, and shared structures long before construction begins.
IMKAT Homes stays up to date on local and state ADU regulations so homeowners can make informed decisions based on both today’s rules and tomorrow’s opportunities.
Looking Ahead for Sonoma County ADUs
Sebastopol’s adoption of AB 1033 is a clear signal that the role of ADUs in California is evolving. What was once viewed primarily as a rental solution is now emerging as a legitimate path to homeownership and property value creation.
As more cities evaluate this option, Sonoma County homeowners considering an ADU may want to think beyond rental income and consider long term flexibility, resale potential, and design choices that align with future local policies.
For now, Sebastopol stands alone in the county, but it may not stay that way for long.
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