Calabasas Zoning and ADU Guide for Homeowners

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

Calabasas allows ADUs and junior ADUs on lots with a single-family home, and on lots with an existing duplex or multifamily units, but California’s housing department told the city in May 2026 that parts of its ordinance conflict with state ADU law. This guide summarizes what the city publishes about ADUs, what the state review letter flagged, and what that means for a homeowner who wants to build, legalize or sell.

Because state law overrides conflicting local limits, confirm the current rules with the city before you design anything.

Calabasas ADU rules at a glance

Where allowed	Lots with an existing or proposed single-family dwelling; also lots with an existing duplex or multifamily units (JADUs only within a single-family home)
ADU size on the city’s page	An existing or additional space of 1,200 square feet or less
JADU	500 square feet or less, within the existing single-family home; separate cooking facilities (efficiency kitchen) and a separate exterior entrance; bathroom may be shared or separate
Pre-approved plans	Available online at no cost; the city says they reduce pre-construction fees and plan check time
Custom ADU plans	Prepared by a licensed California design professional, with the Custom ADU Checklist and Submittal Requirements completed
How to submit	Electronically through the city’s portal; ADUs require complete building plans and a formal review before permits issue
Contact	BuildingSafetyInfo@CityofCalabasas.com or (818) 224-1600, ask for Building and Safety
Zoning code	Calabasas Municipal Code Section 17.12.170 and the development table in Section 17.11.170, adopted by Ordinance No. 2020-382
State review	California HCD review letter dated May 4, 2026 lists provisions it found inconsistent with state ADU law

What the city says about ADUs and JADUs

The city’s ADU page says ADUs and junior ADUs are allowed on properties with an existing or proposed single-family dwelling, and ADUs are also permitted on lots with an existing duplex or multifamily units.

A JADU is limited to space of 500 square feet or less within an existing single-family home, with an efficiency kitchen and its own exterior entrance.

The page describes an ADU as an existing or additional space of 1,200 square feet or less, and it lists conversion of an existing legal accessory structure as one way to create one. It does not publish height, setback or parking numbers, so ask Planning for the current figures.

Pre-approved plans versus custom plans

Calabasas offers pre-approved ADU plans that you can obtain online at no cost. The city says they cut pre-construction fees and shorten plan check, so permits can issue faster.

A custom ADU needs plans prepared by a licensed California design professional that comply with city and state codes and include detailed documentation. You complete the Custom ADU Checklist, answering the first eight questions affirmatively, and the Custom ADU Submittal Requirements with the signature page. All Building and Safety applications are submitted electronically.

The state’s May 2026 review of the city’s ordinance

California’s Department of Housing and Community Development reviews local ADU ordinances. Its letter of May 4, 2026 on Calabasas Ordinance No. 2020-382 lists 20 areas it found noncompliant or outdated.

Among them: references to repealed code sections, omission of recent state legislation, a separate zoning clearance requirement that conflicts with the 60-day approval deadline, a subjective requirement that the ADU conform in design to the main home, a rear-yard site coverage limit that would not allow an 800 square foot detached ADU, front setback and height provisions, a parking exception that is missing, the JADU owner-occupancy rule, permit expiration language, and impact fee measurement and the exemption for ADUs of exactly 750 square feet.

For a homeowner the practical takeaway is simple. State ADU law sets a floor that cities cannot go below, so a local limit that conflicts with it may not be enforceable. But the city’s text may not yet reflect that. Ask Planning which provisions are currently applied, and bring up the state letter if a staff answer seems stricter than state law.

State law basics worth knowing

California generally requires cities to approve a complete ADU application without discretionary review within 60 days, and the HCD handbook explains the minimum size, setback and parking protections that apply statewide. The handbook is the best neutral reference when a local answer seems unclear.

Garage conversions and old second units

A converted garage or a backyard studio built without a permit is common in older homes. Ask the division what permits exist for each structure, then ask Planning whether the structure could qualify today. Legalizing can mean plans, inspection of concealed work, corrections for fire and life safety and fees. The result is not guaranteed, so some owners disclose the unit and sell as-is instead.

Questions to ask the city before you design

• Which provisions of Section 17.12.170 is the city applying given the state’s May 2026 letter?
• What are the current height, setback and parking requirements for my lot?
• Does my existing garage qualify for conversion without changing its footprint?
• What are the current plan check, permit and impact fees at my size?

Property tax on new construction

A newly built ADU is generally reassessed as new construction, so the county assessor may increase the property’s taxable value. See our Los Angeles County property tax guide for how reassessment works, and ask the assessor about your specific project.

Related Calabasas guides

Permits for an ADU follow the process in our Calabasas building permits guide, and complaints about unpermitted units are handled as described in our Calabasas code enforcement guide.

ADUs, garage conversions and selling a Calabasas house

A permitted ADU can add rental income and buyer appeal, while an unpermitted one can complicate financing and appraisal. Because an ADU generally cannot be sold separately from the main home, its value comes only through the sale of the whole property. See our unpermitted work guide and Prop 13 guide. If you own a Calabasas house with an old backyard unit or garage conversion:

• Find out what the city has on file for each structure.
• Ask whether current ADU rules would allow what is there.
• Get a rough cost to correct and permit it.
• Decide whether legalizing first or selling as-is fits your timeline.

How to sell a house in Calabasas

1. Check which structures, additions and conversions on the property have city permits.
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 repairs, permit cleanup or showings required.

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

Frequently asked questions

Can I build an ADU in Calabasas?

Yes. The city allows ADUs and junior ADUs on lots with a single-family home, and ADUs on lots with an existing duplex or multifamily units.

How big can a Calabasas ADU be?

The city’s page describes an ADU as 1,200 square feet or less, and a JADU as 500 square feet or less within the existing single-family home. State law protects at least an 800 square foot ADU.

Does Calabasas offer pre-approved ADU plans?

Yes. The city says pre-approved plans are available online at no cost and reduce pre-construction fees and plan check time.

Did the state find problems with Calabasas’ ADU ordinance?

California HCD’s letter dated May 4, 2026 listed 20 areas where it found the ordinance noncompliant or outdated under state ADU law.

How do I submit an ADU application in Calabasas?

Electronically through the city’s portal. ADUs require complete building plans and a formal review before permits issue.

Who do I contact about a Calabasas ADU?

Email BuildingSafetyInfo@CityofCalabasas.com or call (818) 224-1600 and ask for Building and Safety.

Can I sell my Calabasas 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 Calabasas
• We Buy Houses in Los Angeles County
• Los Angeles County Property Tax Guide
• Calabasas Building Permits Guide
• Calabasas Code Enforcement Guide
• Hidden Hills Building Permits Guide
• La Cañada Flintridge Building Permits Guide
• All California Guides

Sources

• City of Calabasas: ADU – Accessory Dwelling Unit
• California HCD: Review of the City of Calabasas ADU Ordinance (May 4, 2026)
• California HCD: Accessory Dwelling Unit Handbook (March 2026)
• City of Calabasas: Building and Safety FAQs and Tips

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