Multifamily and Duplex Properties for Sale in Contra Costa County: Zoning and Rent Rules
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What multifamily in Contra Costa County looks like
Contra Costa’s apartment market splits by geography. West county has older fourplexes and small buildings in Richmond, San Pablo and El Cerrito. Central county has garden complexes and BART-area mid-rises in Concord, Pleasant Hill, Walnut Creek and the unincorporated Contra Costa Centre. East county has newer complexes and duplex tracts in Antioch, Pittsburg, Bay Point and Brentwood. Rent rules vary just as much, from Richmond’s local rent board to cities that rely only on state law. See financing 2-4 unit properties and apartment building loans.
Rent rules: which cities have local caps
The Attorney General’s rent cap page places Contra Costa in its San Francisco Area region for the statewide cap. That cap is 6.3% for increases from August 1, 2025, and 8.8% for increases from August 1, 2026 through July 31, 2027. The same page lists three Contra Costa cities with their own caps:
| Jurisdiction | Local rule (per AG chart unless noted) | Our guide |
|---|---|---|
| Richmond | 1.5% for increases from Sept. 1, 2026 to Aug. 31, 2027 | Richmond |
| Concord | 5% every 12 months | Concord |
| Antioch | 60% of CPI change, max 3%, recalculated by the city | Antioch |
| San Pablo | No local cap; annual rent registry and rental inspection program (city mailer) | San Pablo |
| Other cities | State law baseline; check city programs | Walnut Creek · Pittsburg · El Cerrito · Pleasant Hill · Martinez |
| Unincorporated county | State law baseline | Bay Point · El Sobrante · Rodeo · Pacheco |
San Pablo. The city’s rental regulations mailer says a Rent Registry Ordinance adopted in May 2023 requires every covered unit to be registered each year. A Residential Health & Safety inspection program covers rentals at least three years old, with inspections also at sale and after unanswered repair requests. The city’s 2025-27 workplan lists a local just cause ordinance and an anti-harassment ordinance as priorities.
We found no rent cap for unincorporated Contra Costa County on the AG chart. Covered units there follow AB 1482. See our AB 1482 guide and just cause eviction guide.
Where the zoning allows it: unincorporated county
Division 84 names its multifamily districts by maximum density.
| District | Units allowed | Key standards |
|---|---|---|
| D-1 Two-Family | One detached duplex per lot, plus R-6 uses | 8,000 sq ft minimum lot. Two covered spaces per unit |
| M-29 Multiple Family | Up to 29 units/acre, at least 1,500 sq ft of land per unit | 10,000 sq ft lot for apartments. 35% coverage. 30 ft height, 20 ft within 50 ft of single-family zoning |
| M-17, M-12, M-9, M-6 | Lower-density multifamily (Chapters 84-28 to 84-31) | Confirm each chapter’s density and height |
| N-B, R-B, C business districts | Buildings with 3+ apartment units by land use permit | Mixed use on commercial land |
| T-1 Mobile Home Park | Mobile and manufactured home parks | Chapter 84-68 |
| HE-C Housing Element Consistency | Sites rezoned in 2024 for the 2023-2031 Housing Element inventory | Densities per the Housing Element (Chapter 84-92) |
M-29 permits multifamily buildings, duplexes and ADUs by right, but not hotels or motels. Medical offices and clinics need a land use permit.
Inclusionary housing. Chapter 822-4 requires 15% inclusionary units in rental and for-sale projects of five or more units. In rental projects, at least 20% of those units go to very low income households, with restrictions lasting 55 years. Projects of 5 to 125 units may pay an in-lieu fee, due before the first building permit. Projects of one to four units are exempt.
ADUs. The Board adopted Ordinance 2025-07 on May 13, 2025. It amends Chapter 82-24 to match state ADU law on residential and mixed-use lots. See our ADU investment guide and our SB 9 lot split guide for the state framework. We did not verify county-specific SB 9 standards.
Transfer taxes and closing costs
The Clerk-Recorder charges $0.55 per $500 countywide. Richmond adds a tiered city tax on full value: $7 per $1,000 under $1 million, $12.50 to $3 million, $25 to $10 million and $30 above. El Cerrito adds a flat $12 per $1,000. On a Richmond apartment building over $3 million, the city tax is a significant line item. Under Proposition 13, a sale generally resets the assessed value.
Older buildings, balconies and seismic
West county has many pre-1960 wood-frame buildings, and central county has 1960s and 1970s garden complexes with exterior stairs and walkways. Buildings of three or more units with elevated balconies need SB 721 inspections. Get an engineer’s view on seismic retrofit for soft-story buildings near the Hayward and Concord faults. In San Pablo, the city inspection program can turn up repair items at sale.
Underwriting a Contra Costa multifamily purchase
- Confirm city or unincorporated status and which rent rule applies (Richmond, Concord, Antioch or state law).
- In San Pablo, confirm rent registry filings and any open RH&S inspection items.
- Classify each unit and model increases under the local cap or the 8.8% statewide cap.
- Check zoning (D-1, M-29 through M-6, HE-C or a city zone) and ADU potential.
- Collect leases, the rent roll and two years of statements, and get estoppel certificates.
- Add Richmond or El Cerrito transfer tax and reassessed property tax in our rental property analysis.
Questions people ask
Which Contra Costa cities have rent control?
The Attorney General’s chart lists Richmond, Concord and Antioch with local caps. Richmond’s is 1.5% for increases from September 2026.
What is the statewide cap in Contra Costa County?
8.8% for increases from August 1, 2026 through July 31, 2027, under the AG’s San Francisco Area region.
Does San Pablo have rent control?
No local cap. San Pablo requires annual rent registry filings and runs a rental health and safety inspection program.
How many units can I build in the county’s M-29 district?
Up to 29 units per acre, with at least 1,500 square feet of land per unit and a 10,000 square foot minimum lot.
Does the county require affordable units in new apartments?
Yes. Projects of five or more units must make 15% inclusionary, or pay an in-lieu fee for projects up to 125 units.
What transfer tax applies in Richmond?
The county tax plus Richmond’s city tax, which runs from $7 to $30 per $1,000 of full value depending on the price.
Can I build a duplex in unincorporated Contra Costa?
Yes. The D-1 district permits a duplex on an 8,000 square foot lot, and M-29 also permits duplexes.
Sources & notes
- California Attorney General, Rent Caps
- City of San Pablo, Rental Regulations and Tenant Protections mailer
- Contra Costa County Ordinance Code, Division 84, Chapters 84-22, 84-26 and 84-92 (GoCodebook)
- Chapter 822-4, Inclusionary Housing
- CEQAnet, Ordinance 2025-07 ADU Ordinance
- Contra Costa Clerk-Recorder, Documentary Transfer Tax with Richmond and El Cerrito pages
Note: Local rent caps change yearly. Check the city program before serving a notice.
General information, not legal or tax advice. Last reviewed October 2026 by Matthew Martinez.
Related: Contra Costa County real estate guide · Commercial real estate in Contra Costa County · Multifamily investing guide · Investor services
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