Commerce Zoning and ADU Guide for Homeowners

Last updated November 13, 2026. Reviewed by the Cash Home Buyers CA team.

Commerce regulates accessory dwelling units in section 19.07.090 of its zoning code, and in December 2025 the state housing department told the city its ADU ordinance on file dated from 2020 and might be out of compliance with current state law. This guide summarizes what the published zoning code says about ADUs and junior ADUs, what the state letter and a 2025 city ordinance mean for you, and what to do if you own a home with a converted garage or an older unpermitted unit.

Because the code has been amended, confirm every number with the city before you design.

Commerce ADUs at a glance

Governing law	Commerce Municipal Code section 19.07.090 and Government Code section 66314 and following
2025 update	Ordinance No. 829 (ZTA 25-05) amends Chapter 19.07 ADU provisions to comply with state law
Where allowed	Single-family lots; multifamily and mixed-use residential lots with a multifamily dwelling; JADUs only on single-family lots
Detached ADU height	16 feet in the published code
New ADU setbacks	4 feet side and rear; existing structures converted may keep their setback
JADU size	Up to 500 square feet; one bedroom
City form	ADU-JADU Application 2025 on the Planning Applications page

What section 19.07.090 says

As published, the code allows ADUs on single-family lots and on multifamily or mixed-use lots with a multifamily dwelling, and JADUs only on single-family lots.

It bars minimum lot-size requirements, caps detached ADU height at 16 feet and requires 4-foot side and rear setbacks for new construction, while conversions of existing space may keep the existing setback. A JADU may not exceed 500 square feet or one bedroom.

In the low-density R-1 zone it lists a conversion within existing space, a new attached or detached ADU, a JADU, or a JADU plus a detached new ADU of no more than 800 square feet.

In R-2 and R-3 it allows up to two detached ADUs on a multifamily lot, plus conversions of non-livable space up to 25 percent of the existing units.

Why the numbers may have changed

HCD’s December 5, 2025 letter says Commerce’s most recent ADU ordinance on file with the state was from 2020, that state law has changed since, and that a non-compliant ordinance is null and void so the state standards apply.

The city’s code listing now shows Ordinance No. 829, which amends the ADU provisions to comply with state law. We could not read that amendment’s text, so treat the published figures above as the older baseline and confirm current limits with Planning at (323) 722-4805.

State rules that matter to owners

Per HCD’s summary: impact fees are barred on ADUs of 750 square feet or less and JADUs of 500 square feet or less, and fees on larger ADUs must be proportional to the primary home.

A city must tell you within 15 business days whether an application is complete, and a complete application is deemed approved if not acted on within 60 days. A city may not require parking for a JADU, and a deed restriction or HOA review cannot be imposed on an ADU.

How to start in Commerce

1. Confirm your zone

Ask Planning to confirm your zoning and any easement or utility constraints.

2. Get current standards in writing

Size, height, setbacks and parking should be confirmed against the amended ordinance and state law.

3. File the application

Use the city’s ADU-JADU Application 2025, then plan check through Building and Safety. See our Commerce permits guide.

State ADU law and Commerce

California’s ADU statute, Government Code section 66314 and following, sets a floor that every city must follow, and local ordinances fill in the details.

The state requires ministerial review within 60 days of a complete application, bars a city from requiring more than a limited set of standards, and generally allows an ADU or conversion inside existing space without added setbacks.

The California Department of Housing and Community Development (HCD) publishes a handbook and keeps a list of the state requirements. Because state law changes often, treat the city’s current ordinance and handout as the final word on size, height, parking and fees for your lot.

ADUs, garage conversions and selling a Commerce house

Many older homes have a converted garage or a backyard unit built without permits. Buyers and lenders ask about them, and California sellers generally disclose known unpermitted work. Our guide to selling as-is with unpermitted work explains the rules, and our Prop 13 guide explains how new construction can affect property tax. Before you list:

• Check city records for permits on any ADU, conversion or addition.
• Ask Planning whether the structure could qualify under current rules.
• Estimate plans, fees and corrections needed to legalize it.
• Compare that with selling as-is and letting a cash buyer take on the legalization.

Questions to ask Planning before you design

• Does my lot and zone allow an ADU, a junior ADU, or both?
• Is a pre-approved or pre-reviewed ADU plan available?
• What are the current impact, utility and school fees for the size I am considering?
• Can my existing garage or accessory structure be converted without changing its footprint?
• Are there fire, slope, easement or utility constraints on my lot?

Junior ADUs and garage conversions in more detail

State law treats a junior ADU as a unit of up to 500 square feet created inside the walls of an existing or proposed single-family home, with an efficiency kitchen and a recorded restriction that keeps it from being sold apart from the house.

A garage conversion is a different path: the unit replaces the garage, and state law generally does not require the city to demand replacement parking. Both are common sources of unpermitted space in older Commerce neighborhoods, which is why buyers’ agents and appraisers ask for the permit record.

If a conversion was done without a permit, the usual fix is to submit as-built drawings, pay the fees and pass inspection, which can take months and cost real money.

Fees, utilities and property tax

State law limits the impact fees a city can charge on smaller ADUs and on conversions of existing space, and it limits when a separate utility connection can be required.

Larger new units can still carry impact fees, school fees and water or sewer connection charges, so ask for an itemized estimate before you commit to plans. New construction is generally reassessed for property tax under Prop 13, which means an ADU can raise the bill for the whole property. Our Prop 13 guide explains how reassessment works.

Why ADUs matter for resale

A permitted ADU can add rental income and appeal for some buyers, but an unpermitted one can complicate financing and appraisal. Lenders typically want permitted living area, and an appraiser may not count unpermitted space.

Because an ADU generally cannot be sold separately from the main home, its value comes through the sale of the whole property.

If you inherited a house with an old backyard unit, or bought one with a converted garage, check what the city has on file before you decide how to sell. Our probate home sale guide covers inherited property.

How to sell a house in Commerce

1. Check which structures on the property are permitted ADUs, conversions or unpermitted.
2. Collect permits, plans and any city notices.
3. Request a no-obligation cash offer for the house as it stands.
4. Choose your closing date.
5. Close with no legalization, repairs or showings required.

See also our Commerce page and the Los Angeles County hub.

Frequently asked questions

Does Commerce allow ADUs?

Yes. The published code allows ADUs on single-family lots and on multifamily or mixed-use lots with a multifamily dwelling.

How tall can a detached ADU be?

The published code caps detached ADU height at 16 feet, but the ordinance was amended in 2025, so confirm with Planning.

How big can a JADU be?

Up to 500 square feet and one bedroom, in both the published code and the state definition.

Are impact fees charged on small ADUs?

State law bars impact fees on ADUs of 750 square feet or less and JADUs of 500 square feet or less.

What did HCD tell Commerce in 2025?

HCD’s December 5, 2025 letter said the city’s ADU ordinance on file was from 2020 and might not comply with current state law.

Can I sell my Commerce house with an unpermitted ADU or garage conversion?

Yes. You can disclose it and sell as-is, including to a cash buyer. Our statewide guide explains the disclosure rules.

More guides

• We Buy Houses in Commerce
• We Buy Houses in Los Angeles County
• Los Angeles County Property Tax Guide
• Commerce Building Permits Guide
• Commerce Code Enforcement Guide
• All California Guides

Sources

• Commerce zoning code, Chapter 19.07 (section 19.07.090)
• Commerce Municipal Code listing, including Ordinance No. 829
• City of Commerce: Planning Applications
• California HCD: Letter of Technical Assistance, December 5, 2025
• California HCD: Accessory Dwelling Units

This guide is general information from public sources, not legal advice. Confirm current rules, fees and hours with the city.