Cities | Concord

Concord, California Multiplex Rules 2026: Zoning, Lot Sizes, ADUs, SB 9, Apartments, Tenant Protections and Fees

Concord, California is a city of 123,261 people in Contra Costa County. Its zoning rules are Title 18, the Development Code, of the Concord Municipal Code, published by General Code. Three facts matter for a project here. Apartments in the RM and RH districts need only a zoning clearance, a staff check with no hearing, at up to 100 homes per net acre in RH. The City applies the state duplex and lot split law, SB 9, through a handout, because its code has no SB 9 section. And the City caps rent increases on covered rentals and requires relocation payments, which changes the cost of replacing rented homes. This page summarizes the ways to build two, three, four or more homes on a Concord lot. The seven guide pages below cover each topic in depth.

Concord Guide Pages

Start With State Law and the City Code

Four state laws set the minimum Concord must allow on a house lot or a small site. SB 9 (2021) allows two main homes on a lot in a single-family zone, a split into two lots, or both, approved by staff with no hearing. ADU law sets the accessory dwelling units (ADUs), second homes on a lot, and junior ADUs a city must allow; a junior ADU is a unit of 500 square feet or less inside a house. SB 684 and SB 1123 allow maps of up to 10 lots with 10 homes. The state density bonus gives extra homes to projects that include affordable homes.

These laws apply to every city. Government Code 65852.21 defines a local agency as a city "whether general law or chartered," and the ADU statutes use the same words. Concord is a general law city, one that runs under the state's general laws for cities and has no charter of its own. The sewer chapter of its code defines the City as "a municipal corporation and general law city organized and existing under the constitution and laws of the state."

The City has written two of these laws into its code. Section 18.200.180 is the ADU section, last amended by Ordinance 23-8 in October 2023, and Chapter 18.185 holds the density bonus beside the City's own affordable housing rule. SB 9 appears once in Title 18, where the design review chapter exempts "Residential development eligible for ministerial approval under the California HOME Act (SB 9)." Ministerial approval means a staff check against fixed rules. A search of Titles 17 and 18 found no section on urban lot splits, small-lot maps or SB 79, the 2025 law on housing near transit stops. HCD, the state housing department, says in its SB 79 advisory that the law's provisions "will take effect on July 1, 2026, in Alameda, Los Angeles, Sacramento, San Francisco, San Mateo, Santa Clara, and San Diego Counties." Contra Costa County is absent from that list. HCD's list of affected cities under the Housing Crisis Act includes Concord, so the state rule that a housing project must replace the protected homes it removes applies here.

Concord in Numbers

The US Census Bureau's Vintage 2025 city file estimates 123,261 people in Concord on July 1, 2025, down from a 2020 estimates base of 125,402. That is a loss of 2,141 people, or 1.7 percent (VanPlex arithmetic: 125,402 minus 123,261, divided by 125,402). In that file Concord is the 50th largest city in California, after Vallejo (123,287) and ahead of Fairfield (122,489). The next cities down the list are Thousand Oaks (122,230) and Berkeley (121,911). Contra Costa County as a whole has 1,170,070 people.

The Housing Element is the City's housing plan. The City's Housing Element page says "The City Council adopted the certified HEU on August 22, 2023," and that on October 23, 2023 HCD found it "to be in substantial compliance with state housing element law." The City's overlay page counts "ten individual parcels totaling approximately 28 acres with an estimated 1,000 potential housing units" in the fair housing overlay adopted in March 2026. The City's yearly housing progress report was not read for this guide, so this page gives no count of permits issued.

The Ways to More Homes Compared

Sources: Concord Development Code Section 18.30.020, Section 18.200.180, Chapter 18.155, Chapter 18.105 and Chapter 18.120; the City SB 9 handout; Government Code 66499.41.

Zoning Districts

Title 18 sorts residential land into Rural Residential (RR), Residential Single-Family (RS), Residential Low Density (RL), Residential Medium Density (RM) and Residential High Density (RH) districts. The number after RS is the lot size in thousands of square feet, from RS-6 at 6,000 to RS-12 at 12,000. Density is counted in homes per net acre, the part of a site that can be built on: up to 10 in RL, 11 to 32 in RM and 33 to 100 in RH. Homes are also allowed in the North Todos Santos district, three commercial districts and two downtown districts.

Each use in each district has one of four permit levels. A zoning clearance and an administrative permit come from Planning Division staff. A minor use permit goes to the Zoning Administrator and a use permit to the Planning Commission, each at a public hearing. Five overlay districts add further rules. The zoning districts page has the full table.

Lot Sizes and Subdivisions

An RS-6 lot needs 6,000 square feet, 60 feet of width and 85 feet of depth. Smaller lots are possible through a small lot subdivision: from 1,920 square feet in RS and RL and from 1,440 square feet in RM, CMX and CO, with a planned development use permit from the Planning Commission. Title 17 sends a tentative parcel map, the first drawing of a land division, of four or fewer parcels to the Zoning Administrator and a map of five or more to the Planning Commission, each at a noticed public hearing. A tentative map approval lasts 24 months and may be extended for up to six years.

Land with an average slope of 30 percent or more may not be developed, and land at 20 percent or more is limited to one house. The lot size and subdivisions page covers the small lot table, map steps, map fees and SB 9 lot splits.

ADUs and SB 9

A Concord ADU may have up to 1,000 square feet on a lot under 12,000 square feet and 1,200 square feet on a larger lot. A detached ADU may be 16 feet tall, or 18 feet near transit, with side and rear setbacks of four feet. The City processes the building permit within 60 days of a complete application. Six pre-approved detached plans, from 205 to 874 square feet, are offered at no charge for the plans. Parts of the City section date from 2023 and are narrower than current state law on owner occupancy, the number of units and appeals. State law controls where the two differ.

For SB 9, the City handout says "SB 9 applies only to parcels zoned Residential Single-Family (RS) or Rural Residential (RR)," and that "The City of Concord is currently refining its SB 9 ordinance, and the following instructions are subject to change." The Housing Element's programs promise an ordinance "to implement the provisions of SB 9 to establish ministerial review procedures for proposed lot splits of existing single-family residential lots by July 2026." No such ordinance is in the Ordinance List. The ADUs and SB 9 page has the details.

Three or More Homes

Multifamily housing is a permitted use with a zoning clearance in RM and RH. In the commercial and downtown districts it needs a zoning clearance on sites listed in the Housing Element and a use permit elsewhere. The Transit Station Overlay adds up to 25 percent to the density of the base district within one-half mile of the perimeter of a station on BART, the regional rail system, for projects that meet the objective design standards, the City's fixed design rules for housing. The Affirmatively Furthering Fair Housing overlay requires 20 to 60 homes per net acre on ten listed properties.

Every residential project of five or more units must include affordable homes, 15 percent of ownership units or 6 percent of rental units, or use one of the alternatives in the code. From July 1, 2026 the in-lieu fee, paid in place of building the affordable homes, for projects of 10 units or greater is $20.13 per gross square foot for ownership projects and $15.10 for rental projects. The three or more homes page covers the overlays, the design standards and the affordable housing rule.

Setbacks, Height and Parking

A house in the RS districts needs a 20-foot front setback and may be 30 feet tall. In RS-6 to RS-10 the interior side setbacks are 5 feet and 10 feet. Lot coverage is limited to 35 percent in RS-6 through RS-8. RM buildings may be 40 feet tall and RH buildings 67 feet, the height row that Ordinance 26-1 amended on February 10, 2026. A new house with four bedrooms or fewer needs at least two enclosed garage spaces. Multifamily parking is 1 space per studio, 1.5 per one-bedroom unit and 2 per two or three-bedroom unit, plus 1 guest space for each 3 units. The parking, setbacks and height page has every district.

Tenant Protections

Chapter 19.40, the Residential Tenant Protection Program, was amended by Ordinance 24-3 in March 2024 and Ordinance 25-3 in April 2025. Rent on a covered unit may rise by no more than 5 percent in a 12-month period. Rent stabilization leaves out units with a certificate of occupancy, the City document that allows a building to be occupied, issued after February 1, 1995. Just cause for eviction, the rule that a landlord needs a reason listed in the ordinance to end a tenancy, still covers them. A landlord who ends a tenancy to demolish a covered unit owes three times the fair market rent published by HUD, the federal housing department, plus a $3,000 moving stipend. ADUs are exempt from the program. The yearly rent registry fee from July 1, 2026 is $89 per unit for units under both parts of the program. The rent stabilization and tenant protections page explains what this means for a site with renters.

Permits and Fees

An appeal of a planning decision must be filed within 10 calendar days, and an approval that is not used within 24 months expires. Most planning applications are billed at actual staff hours against a deposit. The fee schedule effective July 1, 2026 lists a park land fee of $16,691 per home in the low density designations, $11,470 in medium density and $9,914 in high density, and a sewer capacity fee of $6,215 for a single-family home or three-bedroom apartment. The permits and fees page lists who decides each application and the other charges.

The Naval Weapons Station Reuse Area

The reuse site of the former Concord Naval Weapons Station is in the Study district. Chapter 18.65 calls it "an interim zoning district for the Concord reuse project (CRP) site," and says "No permits or approvals otherwise required under Division II of this title in order to establish new land uses shall be issued prior to adoption of a specific plan or equivalent regulatory document." A specific plan is a detailed plan for one area. No adopted zoning standards for housing on the site exist yet.

Three City releases describe where the project stands. One of May 27, 2026 says the City Council approved a Term Sheet, a summary of the terms of a deal, with the U.S. Navy "regarding the price and payment terms for approximately 2,422 acres of property." One of September 24, 2026 says the Navy approved it, and that work on the Specific Plan "will start this winter, with additional community engagement expected to start in early 2027." One of September 30, 2026 lists the project's elements as "12,272 new homes, 25 percent of them affordable." These are the City's figures for a plan that is not yet adopted.

Recent Ordinances

Source: Concord Municipal Code, Ordinance List, read October 11, 2026.

The newest ordinance in the list is 26-2, passed September 8, 2026, which amends the purchasing chapter. Ordinances passed after that date would not yet show in the online code. The City's agenda system did not answer on October 10 or October 11, 2026, so this guide cannot say what the City Council has scheduled.

Where the Code and City Documents Differ

• RM density. The purpose section of the residential chapter prints 11 to 33 homes per net acre for RM, and the standards table prints 11 to 32.
• ADU rules. The City section requires owner occupancy for ADU permit applications received after December 31, 2024, allows two detached ADUs on a multifamily lot and allows no appeals. Current state law allows more on each point.
• SB 9 deposit. The handout names a $2,000 deposit. The fee schedule effective July 1, 2026 lists $2,500 for an SB 9 preliminary application and $5,000 for SB 9 parcel map review.
• Lot split hearings. Title 17 holds a hearing on every tentative parcel map. State law requires approval with no hearing for an SB 9 lot split.
• In-lieu fee. The City's 2024 summary sheet prints $20 and $15 per square foot. The fee schedule prints $20.13 and $15.10.
• Rent cap date. The code sets the 5 percent cap from April 1, 2025. The City's rent program page describes the cap "as of August 1, 2025."
• Registry fees. A City flyer for fiscal year 2025-26 prints $78, $50 and $33 per unit. The fee schedule from July 1, 2026 prints $89, $57 and $38.

Each sub-page lists the differences for its topic. Where a handout and the code disagree, the code is the adopted law, and where the code and a state statute disagree on ADUs or SB 9, the statute controls.

Limits of This Guide

The code text is the publisher's copy, current through Ordinance 26-2 of September 8, 2026. City Council and Planning Commission agendas were not read, because the City's agenda system did not answer. The General Plan, the zoning map, the Housing Element sites inventory, the Downtown Concord Specific Plan, the Concord Reuse Project Area Plan and the yearly housing progress report were not read. School, water and fire district fees are set by other agencies and are left out. Confirm the zoning of a parcel and the fees on a project with the Planning Division at (925) 671-3152 before you buy.

Where to Go Next

Related on VanPlex: the California multiplex guide, the SB 9 page and the ADU law page.

Frequently Asked Questions

Official sources (checked October 2026)