Multifamily and Duplex Properties for Sale in Santa Rosa: Zoning and Rent Rules

What multifamily in Santa Rosa looks like

Santa Rosa holds the largest rental stock in Sonoma County: duplexes and fourplexes in older neighborhoods near downtown and Railroad Square, garden apartment complexes along the main arterials, newer mixed-use and transit-oriented buildings downtown and near the SMART stations, houses with ADUs across the rebuilt fire areas, and many mobile home parks. The city also has rules that the rest of the county does not, including mobilehome space rent control and a city transfer tax. For two to four units, read financing 2-4 unit properties; for five or more, see apartment building loans.

Where the zoning allows it

Chapter 20-22 sets residential districts and Table 2-2 sets permit levels. Its use table was last amended in the published code by Ordinance 2025-014 in November 2025.

District	Duplex	Multifamily	Density (units per acre)
RR Rural Residential	Permitted	Director use permit	0.2 to 2
R-1 Single-Family	Permitted	Director use permit	2 to 13
R-2 Medium Density Multi-Family	Permitted	Permitted	8 to 30 (shared with R-3)
R-3 Multi-Family	Permitted	Permitted, plus missing middle housing	8 to 30; higher under the General Plan’s mixed-use designation
TV-R Transit Village-Residential	Permitted	Permitted, plus missing middle housing	25 to 40
MH Mobile Home Park	Not allowed	Not allowed	4 to 18
CMU, NMU, SMU, MMU, CN, CG	—	Permitted in most mixed-use zones; CN allows duplexes and apartments	TV-M requires at least 40 per acre

Duplexes by right. The city lists duplexes as permitted in R-1 as well as RR, R-2, R-3 and TV-R, so a two-unit building on a single-family lot may not need a discretionary permit. Lot standards still apply.

Missing middle. Section 20-28.100 allows missing middle housing types in R-3 and TV-R. We did not read its standards.

ADUs and SB 9. ADUs and junior ADUs are allowed in RR, R-1, R-2, R-3 and TV-R under Section 20-42.130, and not in MH. State SB 9 applies to qualifying single-family lots; we did not review a city SB 9 chapter. See our SB 9 lot split guide and ADU investment guide.

Rent rules: state law for apartments, local control for mobilehome spaces

AB 1482. The Attorney General’s rent cap page, updated July 16, 2026, puts Sonoma County under "All Other Counties," with covered units allowed up to 8.6% for increases from August 1, 2026 through July 31, 2027. The page lists no Sonoma County city with local rent stabilization for apartments, and we found no general rent cap or just-cause chapter in the city’s published code. Check with the city before closing in case that changes.

County tenant ordinance. Sonoma County’s Residential Tenancy Protections program is addressed to landlords in unincorporated areas. A Santa Rosa parcel in a county island may be covered by it; one inside city limits generally follows state law.

Mobilehome space rent control. Chapter 6-66 covers parks with two or more rented spaces in the city:

Space rent may rise once in 12 months by 70% of the CPI change, capped at 4%, after Ordinance 2023-009 amended the formula.
Notices of increases go to the Clerk and residents at least 90 days ahead.
On an in-place transfer or a tenancy ending under the Mobilehome Residency Law, rent can be reset by up to 10%.
Owners who are denied a fair return can petition an arbitrator, whose decision is final.
Capital improvement pass-throughs need consent from a majority of occupied spaces.
Spaces under a qualifying long-term lease are exempt.

The city also publishes a November 2025 FAQ on the program.

See our AB 1482 guide and just cause eviction guide.

Santa Rosa rental property rules

Business tax. Under Chapter 6-04, as revised by Ordinance 2024-016, renting more than three units in the city counts as a residential rental business, taxed on gross receipts with a $10,000 maximum.
City transfer tax. Chapter 3-20 charges $2.00 per $1,000, and the measure of value includes debt that stays on the property. That is on top of the County’s $0.55 per $500.
Short-term rentals. Chapter 20-48 states that it aims to preserve the city’s limited housing stock. We did not verify current permit caps.
Historic districts. Older duplexes and conversions in the West End and St. Rose preservation districts are in the -H overlay, with design review and a 35-foot, two-story cap unless approved otherwise.

Fire rebuilds, older buildings and balconies

Many Santa Rosa buildings are new since the 2017 fires, while others near downtown date to the early 1900s. Ask for final inspection records on rebuilt units; our post on rebuild permits and final inspection explains why. For older wood-frame buildings, especially those over tuck-under parking, get a seismic retrofit review. Buildings of three or more units with elevated balconies or walkways need SB 721 balcony inspections.

Underwriting a Santa Rosa multifamily purchase

Confirm the parcel is inside city limits, which decides the city transfer tax and which tenant rules apply.
Add the city tax at $2.00 per $1,000, including assumed loans, to closing costs.
Classify units under AB 1482 and model increases no higher than 8.6% for covered units.
For a mobile home park, pull the Clerk’s filed notices and model space rent at 70% of CPI, 4% at most.
Check unit count against the zone’s density and confirm permits for any ADU; collect leases, the rent roll and estoppel certificates.
Rebuild expenses with reassessed taxes, business tax, insurance and SB 721 in our rental property analysis.

Questions people ask

Is there rent control in Santa Rosa?

Not for apartments beyond AB 1482. Mobilehome spaces are rent controlled under Chapter 6-66.

How much can mobilehome space rent rise in Santa Rosa?

Once a year, by 70% of the CPI change, capped at 4%, with at least 90 days’ notice.

Can I build a duplex on an R-1 lot?

The use table lists duplexes as permitted in R-1, subject to lot and development standards.

What densities apply in R-2 and R-3?

8 to 30 units per acre, with higher densities possible where the General Plan designates mixed use.

Do Santa Rosa landlords pay business tax?

Owners renting more than three units in the city are a residential rental business under Chapter 6-04.

What transfer tax applies to a Santa Rosa apartment sale?

The County’s $0.55 per $500 plus the city’s $2.00 per $1,000, which counts assumed debt.

Does the County tenant ordinance apply in Santa Rosa?

The County program is aimed at unincorporated areas, so it may reach county islands but generally not parcels inside city limits.

Sources & notes

Note: We read the city code through GoCodebook’s 2026 editions. We did not read Section 20-42.130 (ADUs), Section 20-28.100 (missing middle), the FAQ document, or the short-term rental permit sections, and did not confirm whether the city has adopted tenant protections after the code edition we read. 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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