Accessory Dwelling Units (ADU/JADU)

What are the benefits of ADU's?

ADUs provide many benefits to property owners, residents, and their communities at large. ADUs are an affordable housing option, which is usually more affordable than many home types. ADUs don’t require acquiring a new property or major infrastructure. Inexpensive wood-frame construction costs significantly less than new multifamily homes.   Most ADUs are owned and managed by homeowners who live on the premises.  Such landlords are more likely to provide affordable rents to friends or family and much less likely to impose significant increases once the lease is signed.  ADUs can generate wealth by increasing property value.  Over time they could generate a source of income for homeowners to cover mortgage payments.  ADUs can house people of all ages and lifestyles. A person’s housing needs change over time, and ADUs can be adapted for different household types, income levels, and stages of life.  They can also allow seniors to age in place with some independence, even as they require more care or allow extended family members or friends to live near one another while maintaining privacy.  Many ADUs are accessible or able to be adapted to fit specific mobility or health needs.  Small living spaces are well-suited for many young couples, students, and seniors. They provide for intergenerational living for empty nesters or expanding families.  There is flexibility of sharing independent living areas with family members and others.  ADUs are just the right size, since they are generally smaller homes, resulting in cheaper heating, cooling, and utility costs.  Generally measuring between 600 and 1,200 square feet, ADUs work well for the one and two-bedroom homes needed by smaller households (which today account for nearly two-thirds of all households in the United States).  ADUs are compatible with the community and offer a way to include smaller, relatively affordable homes in established neighborhoods. In comparison to building types such as a multifamily apartment building, ADUs provide a more dispersed and incremental way of adding homes to a neighborhood.

What are the types of ADU's?

Detached ADUs. Detached ADUs are newly constructed units that are physically separated from the primary home. 

• The newly constructed unit is separate from the primary structure.
• A minimum of 4’ side and rear yard setbacks from the property line.
• 16’ to 18’ high.
• Up to 1,200 square feet.
• Includes a sleeping, cooking, bathroom, bathing and living areas.
• ADU is exempt from certain impact fees if less than 750 square feet.
• No additional parking can be required if located within one-half mile walking distance of public transit.
• Cannot be used for short-term rental of less than 30 days.
• Subject to the California Energy Code requirement to install solar systems if the ADU is a newly constructed, non-manufactured, detached structure.

Attached ADUs. Attached ADUs are newly constructed units that share at least one wall with the primary home. 

• The newly constructed unit is attached to the primary structure
• A minimum of 4’ side and rear yard setbacks from the property line.
• Includes a sleeping, cooking, bathroom, bathing and living areas.
• Attached ADUs are allowed to be up to two stories with a height of 25 feet, or height limit in the underlying zoning, whichever is lower. This allows an ADU to be built above an attached garage.
• ADU is exempt from certain impact fees if less than 750 square feet.
• Increased floor plan cannot exceed 50 percent of the existing living area.
• No additional parking can be required if located within one-half mile walking distance of public transit.
• Cannot be used for short-term rental of less than 30 days.

Conversion ADUs. Conversion ADUs re-purpose existing space, whether that space is detached or attached to the primary home. D

• Takes an existing space on the property either within the primary structure, a garage or an accessory structure and converts it to an independent unit.
• Has its own entrance.
• Includes a sleeping, cooking, bathroom, bathing and living areas.
• Setbacks are not required for existing garage that is converted to an ADU.
• No additional parking can be required if located within one-half mile walking distance of public transit.
• No replacement parking is required when converting or demolishing a garage, carport or covered parking structure.
• Cannot be used for short-term rental of less than 30 days.

Junior ADUs (JADUs). Junior ADUs are small ADUs of converted existing space less than 500 square feet. 

• Conversion of and existing space within the primary residence to a living unit that can have access directly into the primary residence.
• Has its own entrance.
• Limited to 500 square feet.
• Must have a kitchen, but full-size appliances are not required.
• Not required to have a dedicated bathroom.
• No additional parking can be required if located within one-half mile walking distance of public transit.
• Cannot be used for short-term rental of less than 30 days.

Click here for floorplan inspirations

Does Placentia have Preapproved ADU plans I can use?

The City of Placentia City allows Accessory Dwelling Units (ADUs) and Junior Accessory Dwelling Units (JADUs) as a permitted use in residential zones and lots containing multi-family dwelling units. In compliance with State law, regulations are established in Chapter 23.73 of the Placentia Municipal Code. To help simplify the construction of ADUs in Placentia, the city has developed the pre-reviewed ADU program. Through this program the City is accepting available prototype plans for residents to use to build an ADU on their property. These plans can be submitted for plan check and can be listed as available to utilize through the City's Development Services Department. The plans are intended to save homeowners the expense of having custom plans created and are intended for new construction only. The applicant will be responsible for providing a site plan for their specific property on which the ADU will be located and filling out all applicable portions of the prototype plans including project specific information on the coversheet. The required project specific information includes the APN number, the zoning, and the lot size, as well as the required setbacks among other information, such as the style selected, the window materials, and colors which will be used. The applicant will have the ability to download the site and floorplans plans using the links found on the City’s ADU webpage. Three sets of 24”x36” plans will still need to be submitted to the Building Safety Division for Plan Check Review. No construction is permitted without an approved Building Permit. All applicable plan check and development impact fees still apply. Contact the Planning Department for more information at (714) 993-8124 or click this link Preapproved ADU Plans for more information. 

Where do I start?

Step 1: Determine if an ADU or JADU is allowed on your property.

Generally, if you own a single-family residential property, you are eligible to build an ADU or JADU. If you own a multifamily residential property, you are eligible to build an ADU(s).

Step 2: Define your needs and budget

Homeowners should evaluate the financial aspects of incorporating an ADU to their property. Here are some of the costs associated with building an ADU:

• Construction labor and materials (including demolition and site preparation)

• Architectural design services

• Permit fees

• Development impact fees

• Financing (e.g. lender fees and interest payments)

• Property taxes

Step 3: Evaluate your lot and neighborhood for compatibility

Consider the different types of ADUs and design considerations for each one. ADU's should fit into the neighborhood fabric in terms of architectural style and scale. 

Step 4: Design your ADU or JADU

Step 5: Hire a contractor and define construction costs

Step 6: Apply to the Planning Department. Please refer to submittal requirements linked here ADU/JADU Submittal Requirements and submit in person or through the portal here PERMITS-ONLINE--SMARTGOV-CITIZENS-PORTAL.

ADUs and JADUs Built Without Required Permits

ADUs or JADUs built without required permits before January 1, 2020, may apply for permits to legalize the ADU or JADU. Before applying for permits with Building Safety, a property owner should obtain a confidential third-party code inspection from a licensed contractor to determine the unit’s existing condition and scope of necessary building improvements. Health and Safety Code 17920.3 establishes a Building Safety Safe ADU & JADU checklist for what deems a building substandard and acts as a tool for the property owner to understand what improvements may be necessary as part of the permit process.

If you have any questions, please contact the Building Division at (714) 993-8124.

ADU Information and Resources

Fire sprinklers shall be required for the accessory dwelling unit or junior accessory dwelling unit only if fire sprinklers are required for the residential dwelling.

Energy Code Fact Sheet for ADUs

ADU Sewer Connection Detail

Information on Affordable ADU Loan Program 

City of Placentia Municipal Code - Ch. 23.73 ADUs

ADU Vendor Marketplace (provided by Housing SOCAL)