An attached or detached dwelling unit which provides complete, independent living facilities for one or more persons, including permanent provisions for living, sleeping, eating, cooking, and sanitation on the same parcel as an existing dwelling unit is situated. An accessory dwelling unit may also include an efficiency unit, as defined in Section 17958.1 of the California Health and Safety Code and a manufactured home, as defined in Section 18007 of the Health and Safety Code. An accessory dwelling unit may be established through: (i) construction of a new detached structure; (ii) construction of an addition to an existing single-family dwelling; (iii) conversion of existing space in an existing single-family dwelling; or (iv) conversion of an existing garage or other accessory structure on a lot containing an existing single-family dwelling, provided it is set back at a distance sufficient for fire safety.

If you are interested in building a new accessory dwelling on a property in Westminster, please read the information below.

The Process

For projects that only involve an accessory dwelling unit and/or junior accessory dwelling unit, you may proceed through our combined Planning Division Zoning Clearance and Building Division Permit Plan Check. The steps in the process are summarized below. It is the responsibility of the property owner and hired professional to manage the project and follow all applicable codes and regulations.

Step 1: Design

• Determine if your project is feasible.
• Hire a professional architect or designer familiar with residential construction.
• Begin to design an ADU in compliance with Zoning Code, flood zone requirements (if applicable), and the property owner's goals.

Step 2: Pre-Screen

• Once a preliminary design is completed, contact the Westminster Planning Division, Engineering Division, and Building Division to begin project pre-screening. This process ensures that an ADU application is ready to submit for building plan check. This is not a process to answer conceptual design questions. Please contact the Planning Division directly for design or code-related questions.
• Obtain authorization to proceed to the next step. It is the responsibility of the property owner and hired professional to contact each division for pre-screening.
• Pre-screening appointments are highly encouraged. Contact each division directly to schedule an appointment.
• IMPORTANT NOTE FOR COUNTER SCREENING: Pre-screening takes approximately 45 to 60 minutes to complete. The City Hall counter closes at 5:00 p.m. Therefore, please plan accordingly. Do not arrive at the counter 30 minutes prior to closing or you will be turned away. Also, If you bring more than one ADU for pre-screening, City staff will screen one ADU, then help any other customers in the lobby, then return to pre-screen your remaining ADUs.
• ONLINE SCREENING OPTION:  Online ADU Screening is now available!  You may upload your plans and documents online and the Planning and Engineering Division will prescreen your ADU project.  Please continue to contact the Building Division directly for its requirements and screening before plan check submittal.  Please note that the online screening may not be combined with an in-person screening for subsequent reviews.   Once submitted, the City will provide comments within three (3) business days.

Please see the application form section below for the ADU/JADU application form (Combined Planning Division Zoning Clearance and Building Permit Plan Check Application).  Review the application packet as a whole.  Note however, that for ADU online screenings, the ADU project description/details and contact information is directly entered in the online application while the rest of the application documents must be uploaded as separate attachments.  Please see the Application Form section below for City forms that must be attached.

Go to Westminster Build Online Portal to Submit for ADU Screening!  Click here to view the online portal and register for an account! 

Step 3: Prepare Construction Plans

• After pre-screening, the architect or designer will prepare constructions plans in accordance with California Building Code and Fire Code, which includes framing plans, foundation plans, mechanical plans, electrical plans, plumbing plans, Title 24, energy calculations, etc.

Step 4: Review

• A complete set of construction plans will be formally submitted to the Community Development Department to begin formal review.

Step 5: Construction

• Once construction plans have been approved by all applicable agencies, departments, and divisions, a building permit will be issued to begin construction.
• Inspections will occur during construction.

Application Form

ADU/JADU alone or with a minor room addition to a single-family residence

For projects involving an ADU proposed in conjunction with a minor room addition/remodel to a single-family residence, click the link below to access the application form for the combined Planning Division Zoning Clearance and Building Division Permit Plan Check process. The application includes a checklist of everything you must prepare and submit.

Combined Planning Division Zoning Clearance and Building Division Permit Plan Check Application

Online Screening Applications - Separate City Forms for Upload:

The ADU Online Screening application requires upload of the following City documents:

Acknowledgement Form

Tolling Form

Building Address Request Form

Residential Park Fee Handout

For all other projects involving an ADU proposed in conjunction with other construction, the combined Planning Division Zoning Clearance and Building Division Permit Plan Check process will not apply.

The Planning Division must review and process the project first before proceeding to the Building Division construction plan check process. The Planning Division will review the project through either the Zoning Clearance or Development Review process.

The following projects proposed in conjunction with an ADU are subject to Zoning Clearance:

• Any major construction, addition, or alteration to an individual single-family or two-family dwelling or appurtenant structure, or two-single family dwellings on a single parcel.
• The addition of up to two new units to an existing residential development.
• Additions to multiple-family residential projects not resulting in three or more new units.

The following projects proposed in conjunction with an ADU are subject to Development Review:

• New residential projects with three or more new units.

Click here to access the application forms for Zoning Clearance and Development Review.

For additional detailed information on how to navigate the ADU process, click on the link below to download our complete guide.

ADU Guide

The Zoning Code is unique to each city. Therefore, it is important to read and understand the Zoning Code when proposing any development in a city. Understanding the Zoning Code will help guide your design.

Click the links below to access parts of the Zoning Code that are most applicable to ADUs and JADUs. Not all regulations in the Zoning Code will apply to your specific project. If you need assistance understanding a specific part of the Zoning Code, contact the Planning Division.

Accessory Dwelling Units Development Standards

Residential Zoning District Development Standards

Single-Family Residential Development Standards

Detached Accessory Structure Development Standards

Additionally, click the links below to access development standard tables that compile and summarize the regulations from the Zoning Code sections listed above. The tables are meant as a guide, and are not intended to be a substitute for the Zoning Code.

Development Standards Table for ADUs with Single-Family Residential

The Westminster Community Development Department hosted A Guide to Accessory Dwelling Units Online Workshop on August 30, 2021. The workshop was recorded, and is posted below.

You may access slides from the presentation below 

ADU Presentation Slides

California Architects Board

The California Architects Board website includes several publications for consumers with useful information, such as the Consumers Guide to Hiring an Architect.

Department of Consumer Affairs Contractors State License Board

The Department of Consumer Affairs Contractors State License Board website includes several publications for consumers with useful information, such as Construction Project Checklist, Ten Tips for Making Sure Your Contractor Measures Up, Checklist for Prescreening Contractors, What You Should Know Before Hiring a Contractor.

ADU Frequently Asked Questions

ADU Permanent Ordinance No. 2572

ADU Park Fee Resolution No. 5057

Residential Parks Development Impact Fee

Instructions for Verifying Property Dimensions

How to Find Special Flood Hazard Areas

Easement and Their Effects on Property