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

What multifamily in Knightsen looks like

Knightsen is a rural, unincorporated farming community in East Contra Costa County. LAFCo’s 2008 service review describes it as mostly large-lot single-family homes and farmland, with the county general plan calling for low-density rural use to continue. There are no apartment districts we could find. Multifamily here really means:

• A farm or rural home with a second residence, an ADU or a JADU
• Farmworker dwellings or a farmworker housing complex on agricultural land
• Single-family homes rented long term
• Mobile or manufactured homes, where the county allows them

For financing, see financing 2-4 unit properties and apartment building loans. Rural and agricultural parcels often need specialized lenders.

Where the zoning allows it

Contra Costa County zones Knightsen, mostly in agricultural districts. A 2023 county file on Cummings Road was A-2, and a 2010 file on Sunset Road was A-3. Both carried the Agricultural Lands general plan designation.

ADUs on farmland. Under the county’s 2025 ADU rules, a detached ADU in an agricultural district can be up to 1,200 square feet. An attached garage for it can be up to 800 square feet on parcels of five acres or more or in agricultural districts. A private water or septic system must be approved by the county health officer before the ADU is established. ADUs cannot be rented for under 30 days. See our ADU investment guide.

Second homes. A second single-family dwelling needs a land use permit in A-2 and, based on the 2010 case, in A-3. The Sunset Road project went through a mitigated negative declaration, a reminder that a second house on farmland is a discretionary approval, not a by-right ADU.

Farmworker housing. A-2 allows a farmworker dwelling and a farmworker housing complex by right, and a larger farmworker housing center by permit. These are tied to agricultural operations and are not general-market rentals.

SB 9 rarely applies. The county’s Chapter 88-36 limits two-unit developments to single-family R districts and single-family P-1 areas inside Census urbanized areas. Agricultural parcels in Knightsen generally do not qualify. See our SB 9 lot split guide for where it does.

Rent rules: state law only

There is no local rent control in unincorporated Contra Costa County. The Attorney General’s chart lists only Antioch, Concord and Richmond in the county. Covered Knightsen rentals follow the state cap for the San Francisco area: 6.3% from August 1, 2025, and 8.8% from August 1, 2026 through July 31, 2027. Most Knightsen rentals are single-family homes owned by individuals, which can be exempt with the required lease notice. Housing provided to farm employees may have separate state rules. See our AB 1482 guide and just cause eviction guide.

Knightsen rental property rules

• No local registry. We found no county rental registry or inspection program for Knightsen.
• 30-day minimum for ADUs. ADUs and JADUs cannot be rented short term.
• Short-term rentals of the main house. These need a county permit under Chapter 88-32, which allows them in listed agricultural districts but not on Williamson Act land. Non-hosted rentals are capped at 90 days a year under the county requirements.
• No cannabis grows. Knightsen is in the county’s -CE Cannabis Exclusion district. Tenants cannot run commercial cannabis operations on the land.

Drainage, septic and wells

• Flooding. LAFCo’s 2008 review describes Knightsen as a low area that collects runoff and has flooding and overflow problems. The Knightsen Town Community Services District, formed in 2005 to address drainage, never built facilities. LAFCo approved its dissolution on May 10, 2023 because it lacked a sufficient tax base. Check flood zones, drainage and pad elevations before building a second unit.
• Septic and wells. We did not verify water or sewer service for Knightsen. Where a parcel relies on a well and septic system, their capacity is usually the real limit on adding units, and the county health officer must approve them.
• Older and manufactured homes. Older farmhouses and manufactured homes may need foundation and seismic review. SB 721 applies only to buildings of three or more units.
• Transfer tax. Only the county’s $0.55 per $500 applies.

Underwriting a Knightsen income property purchase

1. Confirm the zoning, parcel size and any Williamson Act contract.
2. Verify permits for every existing dwelling, including second homes and farmworker units.
3. Test well yield and septic capacity before planning any new unit.
4. Check flood zone, drainage and insurance.
5. Classify each rental under AB 1482 and request leases and estoppel certificates.
6. Model returns with our rental property analysis guide, including rural maintenance costs.

Questions people ask

Sources & notes

1. Contra Costa LAFCO: East County MSR, Knightsen CSD chapter (December 2008) and June 14, 2023 dissolution report
2. CEQAnet: SCH 2023040092 and SCH 2010022040
3. County Ordinance Code via GoCodebook: A-2 uses, A-3, Chapter 82-24, Chapter 88-36, Chapter 88-32, -CE
4. California Attorney General, rent caps
5. Contra Costa Clerk-Recorder, Documentary Transfer Tax

Note: We did not confirm water and sewer providers, flood zones, mobile home park locations, or any residentially zoned subdivisions in Knightsen. The A-3 use list was not available online.

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

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