Multifamily and Duplex Properties for Sale in Sebastopol: Zoning and Rent Rules

What multifamily in Sebastopol looks like

Sebastopol’s rental stock is small and mixed: older duplexes and small apartment buildings within walking distance of downtown, apartments over shops in the Central Core, a handful of larger complexes, newer townhome and condominium projects, houses with ADUs, and mobile home parks. The city regulates more of this than its size suggests, with its own mobile home rent rules, a just cause ordinance for large affordable projects and a housing growth cap tied to sewer capacity. For two to four units, read financing 2-4 unit properties; for larger buildings, see apartment building loans.

Where the zoning allows it

Chapter 17.20, adopted with Ordinance 1111 in 2018 and amended through 2026, sets the residential districts. Its use table does not allow two-family dwellings in the four single-family districts.

District	Two-family	Multifamily	Density and height
R1 to R4 Single-Family	Not permitted	Not permitted	From about 1 to about 8.7 units per acre; 30 ft, 2 stories
R5 Single-Family and Multifamily	Permitted	Permitted	Up to 12 units per acre; 30 ft, 2 stories
R6 Multifamily	Permitted	Permitted	About 12 to 17 units per acre; 35 ft
R7 Multifamily	Permitted	Permitted	About 12 to 25 units per acre; 35 ft, or 40 ft and 3 stories for deed-restricted affordable
RMH Mobile Home Park	Not permitted	Not permitted	Mobile home parks permitted
CD, CG, CO	—	Mixed-use housing permitted; standalone housing by use permit	Ground floor on main frontage must be nonresidential

The R1 to R4 lot tables mention duplex lot sizes that may conflict with the use table, so ask Planning before relying on either.

ADUs. Chapter 17.220, most recently amended by Ordinance 1162 in 2026, allows on a multifamily parcel up to eight detached ADUs, but no more than the number of existing units. It also allows one attached ADU in non-livable space for every four existing units. ADUs on lots of 10,000 square feet or more may reach 1,000 square feet. A new section allows ADU condominiums. See our ADU investment guide.

SB 9. State SB 9 can apply to qualifying single-family lots in R1 to R4; we did not review a city SB 9 chapter. See our SB 9 lot split guide.

Growth management. Chapter 17.500 limits new housing allocations to 50 a year and 750 through 2035, or the remaining wastewater capacity under the city’s contract with Santa Rosa if that is lower. ADUs, affordable units and Central Core units are exempt from the annual limit. Senior units, SROs and units under 500 square feet count as half a unit.

Rent rules: state cap, a local just cause rule and mobile home rent stabilization

AB 1482. The Attorney General’s rent cap page, updated July 16, 2026, places Sonoma County under "All Other Counties," allowing covered units up to 8.6% for increases from August 1, 2026 through July 31, 2027. Sebastopol has no local cap on apartment rents.

Chapter 9.36, just cause for large affordable projects. Chapter 9.36, from Ordinances 1159 and 1160 of 2025, is narrow:

It covers only income-restricted units in projects of 40 or more rental units.
Just cause applies from the start of lawful occupancy, with the cause stated in the notice.
No-fault terminations require relocation of three times the greater of fair market rent or actual rent.
The chapter repeals itself on January 1, 2027 unless the city acts.

Chapter 9.28, mobile home spaces. Chapter 9.28, amended by Ordinance 1148 in 2023, limits space rent increases to the lesser of 75% of the Bay Area CPI change or 3% in 12 months, with 90 days’ notice. Larger increases go through a petition and arbitration process. On an in-place sale, rent may rise by up to 10%. Long-term leases that meet Civil Code Section 798.17 are exempt.

Emergency rent limits. After a declared emergency, Chapter 17.290 bars rent more than 10% above the pre-emergency rent. It also bars evicting a tenant to re-rent the unit at a higher price.

See our AB 1482 guide and just cause eviction guide.

Sebastopol rental property rules

Short stays in ADUs. ADUs on multifamily parcels cannot be rented for under 30 days. ADUs on single-family lots approved after July 1, 2017 need a use permit for transient use. JADUs cannot be used as vacation rentals at all.
County tenant ordinance. Sonoma County’s Residential Tenancy Protections program is addressed to unincorporated areas, so it generally does not reach parcels inside city limits.
Transfer tax. The County Recorder applies the County’s $0.55 per $500 in Sebastopol with no added city amount listed, although Chapter 3.08 sets a city rate of $0.55 per $1,000.

Older buildings, sewer and balconies

Many small Sebastopol rentals are older wood-frame buildings, and some sit on hillside lots. Get a seismic retrofit review for raised or soft-story buildings, and budget SB 721 balcony inspections for three or more units with elevated decks or walkways. Because the growth cap is tied to the city’s treatment capacity through Santa Rosa, ask the city early about sewer connection fees for any added unit.

Underwriting a Sebastopol multifamily purchase

Confirm the zone; outside R5, R6 and R7 a second unit may need to be an ADU rather than a duplex.
Classify units under AB 1482 and model increases at or below 8.6% for covered units.
If the property is an income-restricted project of 40 or more units, plan for Chapter 9.36 relocation of three months’ rent and track its 2027 sunset.
For a mobile home park, model space rent at the lesser of 75% of CPI or 3% a year.
Check any planned new units against growth allocations and sewer capacity; collect leases, the rent roll and estoppel certificates.
Rebuild expenses with reassessed taxes, insurance and SB 721 costs in our rental property analysis.

Questions people ask

Is there rent control in Sebastopol?

Not for apartments beyond AB 1482. Mobile home spaces are limited to the lesser of 75% of CPI or 3% a year.

Can I build a duplex in an R3 zone?

The use table does not permit two-family dwellings in R1 to R4. An ADU or SB 9 project may be the path instead.

Who is covered by Sebastopol’s just cause ordinance?

Only tenants in income-restricted units in projects of 40 or more rental units.

How much relocation does Chapter 9.36 require?

Three times the greater of fair market rent or the actual monthly rent.

How many ADUs can go on an apartment lot?

Up to eight detached ADUs, not exceeding the existing unit count, plus one attached ADU per four existing units.

Can I rent an ADU on Airbnb in Sebastopol?

Not on a multifamily parcel. On single-family lots, newer ADUs need a use permit, and JADUs cannot be vacation rentals.

Does Sebastopol cap new housing?

Allocations are capped at 50 a year and 750 through 2035, with ADUs, affordable and Central Core units exempt from the annual limit.

Sources & notes

Note: We read the code through GoCodebook’s October 2026 edition. We did not find a citywide short-term rental chapter in the index, did not review SB 9 implementation, and did not confirm whether Chapter 9.36 has been extended past 2027. The housing stock description is a general observation. See also our Sonoma County multifamily guide and Sonoma County commercial guide.

General information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.

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