What is a Junior Accessory Dwelling Unit? Orange County JADU Guide for 2024

Recent legislation enacted in California has drastically altered the environment for owners of both single-family and multifamily dwellings. In particular, under Assembly Bill Nos. 68 and 881, landowners throughout the state may now construct an Accessory Dwelling Unit (ADU), a Junior Accessory Dwelling Unit (JADU), or both.

Before you continue reading, if all of this jargon is too much for you, here is the definition of an ADU.

Here at GreatBuildz, a free service in Los Angeles that connects homeowners in Los Angeles, Orange County, Ventura or San Diego with reliable general contractors, we get inquiries every day about Junior ADU and garage conversion projects – here are some tips to get you started.

Junior Accessory Dwelling Unit – What exactly is a JADU?

The new California ADU legislation, which took effect on January 1, 2020, allows homeowners to construct a Junior Accessory Dwelling Unit (JADU) in addition to an ADU and the primary residence. The Junior ADU is limited to 500 square feet, which is sufficient for a studio or one-bedroom home. Orange County and its communities in Southern California are following the State’s lead and incorporating these new rules into their local ordinances.

Junior Accessory Dwelling Unit

The rules of California and Orange County indicate that the JADU unit must fit within the existing ‘envelope’ of the primary residence, with the flexibility to add an extra 150 square feet for entry and egress. Let’s elaborate and provide some examples…

If you have an attached garage, it is considered to be within the envelope of the home, so you might convert it into a Junior ADU (maximum 500sf). Alternatively, if you have an extra bedroom (or two) or another area in your home that you’re not using, you could ‘wall it off’ to separate it from the rest of the house and build a JADU out of that space. If neither of these options is feasible, you could consider adding a large bedroom or family room to your home and converting it into a JADU by adding a kitchen, bathroom, etc.

Junior Accessory Dwelling Unit

Orange County Junior Accessory Dwelling Unit Requirements and Guidelines: 

  • Must have separate access from the main house, so you will need to add an entrance door to the JADU, most likely on the side of your property.
  • Junior ADUs can either have their own bathroom or share a bathroom with the primary apartment.
  • Must own a functional kitchen, including:
    • The required kitchen sink must have a drain line with a maximum diameter of 1.5 inches.
    • No appliances requiring natural gas or propane
    • A food preparation counter and storage cabinets of a size commensurate with the dimensions of the JADU.
    • Appliances that do not require a voltage higher than 120 volts
  • No parking is required for the JADU unless the attached garage is converted. If you are converting a garage, you can use an existing driveway to provide replacement parking if it is large enough to accommodate two automobiles.
  • The JADU has a maximum occupancy limit. This means that you, the property owner, must either reside in the primary residence or in the JADU… and cannot rent out both areas. (This restriction refers to a JADU only, NOT an ADU). This paragraph about owner possession states:

The single-family home in which the junior additional dwelling unit will be permitted must be occupied by the owner. The owner may reside in either the surviving component of the structure or the newly formed junior auxiliary housing unit. If the owner is another government body, land trust, or housing group, owner-occupation is not necessary.

You can learn more precise Los Angeles ADU and Junior ADU requirements by examining this city memo: https://planning.lacity.org/odocument/ec892d01-7873-455a-8e15-78a771b2c7ac/ADU Memo 2020 Final 2.26.20 (1).pdf

What is the distinction between an ADU and JADU?

A junior ADU is a simplified, smaller version of an ADU that fits inside the footprint of an existing home. Since there are fewer criteria (e.g., smaller kitchen, no requirement for bathroom, shared utilities with home, etc.), building costs will be reduced. For a line-by-line comparison, see the diagram below (Source: https://www.hcd.ca.gov/policy-research/docs/faqsdujr.pdf).

Difference ADU and JADU

Building a Junior ADU in Orange County

By constructing an ADU and/or JADU, an Orange County single-family home can essentially now be converted into a duplex or triplex! Your property may now include your primary residence, a 1200-square-foot-max ADU, and a 500-square-foot-max junior ADU. Additionally, you may rent two of the three units (remember the JADU comes with an occupancy restriction discussed above).

When it comes to constructing a JADU on your property, the first step is to conduct research and obtain free guidance from a professional source to ensure that you can accomplish your goals in accordance with your city’s regulations. To assist with this, our staff is always available for a free 15-minute phone consultation.

You should then employ a designer or small architecture firm to create your plans so they can be submitted to the City Department of Building and Safety for plan check. These plans should cost between $4,000 and $10,000, depending on your needs.

Concurrently with working with an architect, you should also meet with one or more experienced Junior ADU contractors, who will visit your home to assess your plans and project concept and provide comments on the location restrictions, utilities, size, design, estimated costs, etc. Reviewing our ADU/JADU construction checklist will help you prepare for meetings with contractors.

Upon finalization of your plans, the JADU contractor(s) will provide a thorough estimate and proposal. After your City building department has approved the blueprints and issued a permit, you will choose a contractor and sign a contract for the work. Construction may finally begin.

What is the cost of a Junior Accessory Dwelling Unit in Orange County?

White ADU detached

The price of JADU varies significantly on the materials, features, and size you select. Converting a section of your home will be less expensive than converting your garage.

When constructing a JADU from an attached garage, the foundation, external walls, stucco, and roof are already in place. Consequently, the construction entails tasks such as constructing the fourth wall (where the garage door was), installing any interior walls and ceilings, a kitchenette, bathroom, flooring, windows and doors, plumbing, electrical, heating, ventilation, and air conditioning (HVAC), insulation, and connecting a sewer line.

Depending on the homeowner’s demands and desires, JADU garage conversion costs will range from $50,000 to $80,000. Check out my blog post titled 5 Cost-Saving ADU Tips for some suggestions on how to save money when creating a JADU.

How can I afford a Junior ADU?

There are numerous ways for homeowners to fund the construction of a junior accessory dwelling unit. Clearly, they can cover the cost with their own savings. Or they can fund this construction by taking out a home equity line of credit, arranging a construction loan, or using a home renovation loan which is often a very speedy procedure but comes with a higher interest rate, from a firm like Lightstream or SoFi. For a complete and detailed overview of JADU financing alternatives, visit my other page on the topic.

Related: Los Angeles ADU Financing Guide

How long does it take to build a JADU?

To build a JADU, you can expect the complete project to take 3-6 months, which includes the time to draft the architectural plans, wait for the city to perform plan check, and ultimately, the construction phase – which will take around 2-3 months.

Why are homeowners in Los Angeles constructing JADUs?

Build an ADU for extra income

Converting a piece of your home or your current garage is a very cost-effective option to generate more living space or rental income on your property. Residents of Orange County have diverse intentions and motivations for constructing JADUs.

Some individuals do so in order to provide a separate living space for a family member, such as an aging parent or a college-aged child. Others utilize it as additional room for a guesthouse, office, gym, mancave, woman-shed, music studio, etc. Some seniors are relocating to their JADUs in order to rent out their primary residence and generate retirement income. Others intend to rent out the junior auxiliary dwelling unit for additional rental income.

Local investors are increasingly attracted to JADU investments due to the rental income potential. Even if you are building a JADU for investment purposes, you should not sacrifice construction quality. Choose a licensed, insured, and trustworthy JADU contractor for your job. You’ll want to create rental income and profits for an extended period of time, so bad construction could hinder your capacity to keep your tenants satisfied. In addition, don’t forget to call your insurance agent and add the JADU to your coverage, as well as a policy to protect you against any accidents or damages the tenant may create.

How To Find A JADU Contractor in Orange County

Orange County ADU Reliable Contractor

Here are a few ideas for locating the ideal Orange County JADU builder. It is advisable to seek only local, licensed General Contractors. Other contractors are not qualified or equipped to perform this type of construction, and the use of an unlicensed contractor or handyman is not recommended. Confirm that any contractor you approach has expertise in constructing ADUs or JADUs. You want to select a contractor who has constructed ADUs, JADUs, or garage conversions in Orange County and is therefore familiar with the applicable requirements and potential problems.

When picking a contractor, you should also examine a number of additional factors. Verify on the Contractors State License Board website that each contractor’s license is active, there are no disciplinary charges against it, and it has Worker’s Compensation insurance (if the GC has their own employees). In addition, verify that they are insured and obtain a copy of their insurance certificates.

Request that your contractor gives at least three references for you to contact. Check their internet reviews on Google, Yelp, and other sites. Check out my blog for more information on how to identify a reputable JADU contractor. 10 Guidelines for Employing an ADU Contractor

Related: Garage Conversion ADU Insurance Info

If you want to learn more about the process and costs of building a Junior Accessory Dwelling Unit on your property, please check out my other blog posts below.


When you’re ready to take the next step and talk to a contractor or designer/architect about your specific JADU project in Los Angeles, Orange County, Ventura, or San Diego, please feel free to call one of our friendly GreatBuildz staff at 818.317.3567 or at www.GreatBuildz.com.

Hi, we're Paul and Jon - Co-Founders of GreatBuildz. We believe everyone deserves to find a great contractor, have a stress-free renovation, and enjoy their beautiful new space. There are so many contractors out there and it's often hard to tell the good from the bad... until it's too late. We started our company to help simplify your contractor search and help you have a stress-free renovation experience. We're always available to help, no matter where you are in the process. Click here to learn more about our story.

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