Multifamily and Duplex Properties for Sale in Alameda County: Zoning and Rent Rules

What multifamily in Alameda County looks like

Alameda County has the most layered rental rules in the Bay Area. Oakland, Berkeley, Alameda, Hayward and San Leandro each run their own rent programs. The tri-valley and southern cities mostly follow state law. The unincorporated communities of Castro Valley, San Lorenzo, Ashland, Cherryland and Fairview have their own county rules. The housing stock runs from Victorian duplexes and fourplexes in Oakland and Berkeley to postwar garden apartments in Hayward and San Leandro and newer podium buildings near BART. For financing, see financing 2-4 unit properties and apartment building loans.

Which rent rules apply: city by city

The Attorney General’s rent cap page lists five Alameda County cities with local rent increase limits: Alameda, Berkeley, Hayward, Oakland and San Leandro. Everywhere else, covered units follow the statewide cap. The AG chart puts Alameda County in its San Francisco Area region, where the cap is 6.3% for increases from August 1, 2025, and 8.8% for increases from August 1, 2026 through July 31, 2027.

A city that is not on the AG chart can still have registration, rent review or relocation rules. Check each city’s own program before you buy. Our AB 1482 guide explains the state baseline.

Unincorporated county rent and eviction rules

Just cause, Chapter 3.70. The Board of Supervisors adopted a Just Cause for Eviction ordinance on second reading on February 4, 2025. The county’s tenant protections page says it took effect March 6. The ordinance builds on state just cause law with local additions:

• It covers single-family homes when the landlord owns five or more rental units in the unincorporated area.
• No-fault evictions require two months’ rent in relocation assistance, subject to a $10,000 per-household cap.
• Households with children, seniors 62 and older, people with disabilities or lower-income members get 90 days’ notice for a no-fault eviction.
• Tenants displaced by an owner move-in or substantial remodel get a right of first refusal.
• Landlords must file every just cause termination notice with the Community Development Agency. Skipping that filing can give the tenant a defense in court.

The ordinance does not cap rents and leaves the state rent cap in place. See our just cause eviction guide.

Mobile home parks. The county’s mobile home page says the Mobile Home Space Rent Stabilization Ordinance, updated in April 2017 and amended in 2024, limits space rent increases to 4% a year in most cases in unincorporated parks.

Help for owners. The county Housing & Community Development Department’s owner resources page points unincorporated landlords to a Housing Provider Resource Center and to ECHO Housing’s mediation and its training on the county’s rent review ordinance.

Where the zoning allows it: unincorporated county

Title 17 sets these residential districts. Castro Valley has its own districts in Chapter 17.51.

In R-4, mobilehome parks and SROs need a conditional use permit. On HE overlay sites designated low or mixed income, multifamily projects with 20% lower-income units get by-right approval. Residential parking on those sites is capped at 2.25 spaces per unit.

ADUs. Chapter 17.55 allows, on an existing multifamily lot, conversions of up to 25% of the unit count and up to eight detached ADUs, as long as they do not outnumber the existing units. ADUs must rent for more than 30 days. See our ADU investment guide and our SB 9 lot split guide. We did not find SB 9 standards in the chapters we reviewed.

East County. Outside the Measure D urban growth boundary, new housing on Large Parcel Agriculture land is limited to a 12,000 square foot residential cap, according to the county’s Measure D review. Rural multifamily is effectively not an option there.

Transfer taxes and building issues

The County Clerk-Recorder charges $0.55 per $500 of value countywide. It also collects city taxes on full value: Oakland charges $10 to $25 per $1,000 in tiers, Berkeley $15 or $25, Alameda $12, Albany $15, Piedmont $13, San Leandro $11 and Hayward $8.50. On a large apartment sale in Oakland or Berkeley, the city tax is a major closing cost. Much of the county’s stock is older wood frame, so plan for a seismic retrofit review where a city requires one. Buildings of three or more units with elevated balconies need SB 721 inspections.

Underwriting an Alameda County multifamily purchase

1. Confirm whether the parcel is in a city or unincorporated, and which rent program applies.
2. For unincorporated buildings, collect copies of any just cause notices filed with the county and check relocation exposure.
3. Classify units under the local ordinance or AB 1482 and model increases accordingly.
4. Check the zoning (R-2, R-3, R-4, Castro Valley district or HE overlay) and ADU potential under Chapter 17.55.
5. Collect leases, the rent roll and two years of statements, and get estoppel certificates.
6. Add city transfer tax and reassessed property tax in our rental property analysis.

Questions people ask

Sources & notes

1. California Attorney General, Rent Caps
2. Board of Supervisors, Just Cause Eviction ordinance (Ch. 3.70), Feb. 4, 2025 agenda item
3. Alameda County HCD, Tenant Protections, Mobile Homes and Rental Property Providers & Owners
4. Alameda County Ordinance Code, Title 17 (GoCodebook): Chapters 17.10, 17.14, 17.16, 17.31, 17.51 and 17.55 as linked above
5. Alameda LAFCo Measure D review (March 2022)
6. Alameda County Clerk-Recorder, Real Property Transfer Tax

Note: The ordinance text we reviewed was the version on the February 2025 agenda. Confirm the codified version with the county.

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

Related: Alameda County real estate guide · Commercial real estate in Alameda County · Multifamily investing guide · Investor services