Rosemead Zoning and ADU Guide for Homeowners

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

Rosemead regulates accessory dwelling units under Ordinance No. 995, adopted September 8, 2020, runs an ADU Standard Plans program under Assembly Bill 1332, and publishes a Planning handout with size, height, setback and parking standards. This guide summarizes the city’s ADU handout, the standard plans program and the 2025 state-law changes that California HCD flagged in a letter to the city, and explains what to do if your home has a garage conversion or an older unpermitted unit.

Rosemead ADUs at a glance

Ordinance	No. 995, adopted September 8, 2020 and effective October 8, 2020
Planning Division	(626) 569-2140
Detached ADU, one bedroom or studio	150 to 850 square feet if floor-area ratio permits
Detached ADU, more than one bedroom	Up to 1,200 square feet if floor-area ratio permits
Height, detached	17 feet for one story and 30 feet for two stories, measured from the habitable surface
Side and rear setbacks	4 feet, attached or detached
Parking	One space per bedroom or per ADU, whichever is less, with exemptions in Table 17.30.190.1
Standard plans	Pre-approved detached plans listed at 800, 1,000 and 1,200 square feet

What the city’s ADU handout says

The city’s ADU handout, issued by the Community Development Planning Division, sets the maximum floor area for an attached ADU at 50 percent of the existing primary residence, with an 800 square foot ADU permitted when the primary home is under 1,600 square feet.

Detached units follow the 150 to 850 square foot and 1,200 square foot limits above.

If creating an ADU would push the lot past its floor-area ratio, the handout says an 800 square foot ADU at least 16 feet high with four-foot side and rear setbacks must still be permitted, as long as it meets the other local standards.

Converting an existing permitted structure does not have to meet the standard setbacks if the side and rear setbacks are enough for fire safety, and a second floor cannot sit closer to the line than the first floor.

The handout is undated, and it lists a JADU on site as requiring owner occupancy and notes that the city may impose owner occupancy after January 1, 2025. Treat it as a starting point and confirm current numbers with Planning.

The standard plans program

The city’s ADU page explains that Assembly Bill 1332 required local agencies to develop a program to pre-approve architectural and design plans for ADUs by January 1, 2025. Rosemead accepted plans from design professionals for detached ADUs pre-approved for use throughout the city, listed at 800, 1,000 and 1,200 square feet.

Homeowners buy the plans directly from the design professional for a more streamlined process, and the city says the program continues so more plans can be added. Planning can be reached at (626) 569-2140.

What HCD told Rosemead in December 2025

California’s Department of Housing and Community Development sent the city a letter of technical assistance on its ADU ordinance, dated December 5, 2025.

The letter lists changes in state law since the ordinance was adopted, including a 500 square foot cap on a junior ADU, a requirement that JADUs be rented for terms longer than 30 days, owner-occupancy only where a JADU shares sanitation with the main home, a ban on impact fees for ADUs of 750 square feet or less and for JADUs, and ministerial approval of one ADU plus one JADU per lot in qualifying cases.

It also says that if a local ordinance does not meet state law, state standards apply until the city adopts a compliant ordinance. If your plans depend on a number in the city’s older handout, ask Planning which standard governs your lot.

Garage conversions and unpermitted units

Older Rosemead homes sometimes have a converted garage or backyard unit built without permits. Such a unit can complicate a sale because buyers, lenders and appraisers ask for permit records. Our Rosemead building permits guide explains how the city handles inspections, and our code enforcement guide explains what happens if the city opens a case.

State ADU law and Rosemead

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 Rosemead 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 Rosemead 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 Rosemead

1. Ask the city for the permit record on any ADU or conversion.
2. Collect plans, inspection records 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 repairs, legalization or showings required.

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

Frequently asked questions

Does Rosemead have pre-approved ADU plans?

Yes. The city accepted pre-approved detached ADU plans listed at 800, 1,000 and 1,200 square feet under its Standard Plans program, and homeowners buy them from the design professional.

What setbacks does Rosemead require for an ADU?

The city’s handout lists 4-foot side and rear setbacks for attached and detached ADUs, with relief for converting an existing permitted structure if fire safety is met.

How tall can a detached ADU be in Rosemead?

The handout lists 17 feet for one story and 30 feet for two stories, measured from the habitable surface.

What parking does Rosemead require for an ADU?

One space per bedroom or per ADU, whichever is less, with exemptions listed in Municipal Code Table 17.30.190.1.

Where can I call about ADUs in Rosemead?

The Planning Division at (626) 569-2140.

Can I sell my Rosemead 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 Rosemead
• We Buy Houses in Los Angeles County
• Los Angeles County Property Tax Guide
• Rosemead Building Permits Guide
• Rosemead Code Enforcement Guide
• All California Guides

Sources

• City of Rosemead: Accessory Dwelling Units (ADU)
• City of Rosemead: ADU Handout
• California HCD: Rosemead ADU Ordinance Letter of Technical Assistance, December 5, 2025

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