What Is the Difference Between an ADU and JADU in California?

An Abodu Two interior with upgraded folding doors to create an indoor-outdoor space.

An Abodu Two interior with upgraded folding doors to create and indoor-outdoor space.


February 23, 2024Backyard Living

Navigating sustainable ways to expand your California property can feel like a puzzle. Two pieces of this puzzle are accessory dwelling units (ADUs) and junior accessory dwelling units (JADUs).

While these terms may sound similar, they're not interchangeable. Though both require a separate entrance, the main differences between an ADU and a JADU can be pivotal in guiding homeowners on how best to add to their property extension.

What is an ADU?

Often called a granny flat or backyard cottage, ADUs can be categorized into three types: detached, attached, and conversion.

Detached ADUs are standalone structures. They provide privacy and autonomy, making them a popular choice as short-term rental units or guest houses.

Attached ADUs are extensions of the primary residence. These accessory dwellings are connected to the house, but usually have a separate entrance.

Conversion ADUs transform an existing part of the house, such as a garage or large living area, into a fully independent living space.

What is a JADU?

Think of a JADU as a smaller version of an attached ADU with distinct rules and exemptions—such as no parking requirements and allowance of shared utilities—based on local ordinances.

Capped at 500 square feet, JADUs offer an efficient option to property enhancement, ideal for those seeking a minimal, yet highly functional addition to their main home.

ADU vs. JADU: Key differences

The overarching difference between an ADU and a JADU lies in their integration with the main home and the extent of their independence.

An ADU is a completely separate, self-contained living space. JADUs are more intertwined with the primary residence, sharing bathrooms and certain utility connections (e.g., water, electricity, sewage, etc.).

Check out the many factors differentiating an ADU and a JADU, from floor area to development standards and more.

Unit size

One of the main differences is size. A JADU is a maximum of 500 square feet, so it is compact and often has a studio layout. This limits JADUs to single occupancy.

Standard ADUs can offer more space and state law allows municipalities to set their own size restrictions. The typical upper limit of a standard ADU in most California cities, such as Los Angeles, is 1,200 square feet—more than double a JADU.

Rooms & amenities

California code allows a JADU to share a bathroom with the main house. For amenities, a dedicated parking space is not required and a space-saving efficiency kitchen satisfies JADU ordinances.

As self-contained housing units, ADUs must have essential rooms and amenities, including a full kitchen, private bathroom, sleeping area, and living space. Depending on its proximity to public transit and other criteria, the property owner may have to comply with parking requirements.

Owner occupancy requirements

California law on owner occupancy depends on the type of unit. The homeowner is required to live on-site for a JADU. ADUS are exempt from the owner occupancy mandate, so they offer the property owner more flexibility.


From a budget perspective, JADUs typically cost less due to their smaller size and the repurposing of existing space.

As an entirely independent living space, detached ADUs are a major construction project, which requires a higher upfront investment and longer timeline. Plus, the building permit fees for an ADU often cost more since many jurisdictions calculate their fee schedules by square footage.

The tradeoff for a more expensive ADU is that it has the potential to generate higher rental income than a JADU due to its larger size. In addition, a detached ADU can comfortably support a small family, whereas a junior ADU would not have enough space.


Zoning ordinances apply to both junior ADUs and standard ADUs, but developing a JADU is often simpler.JADUs can only be added to single-family residences and must share a wall with the family dwelling.

In contrast, constructing a detached ADU is similar to a small-scale home-building project. Adding an ADU to your property usually requires more thorough planning and design documentation to secure the proper building permits.

This can include assessments of structural integrity, separate utilities, and compliance with stricter building codes. The specific community development criteria vary across different jurisdictions statewide.

Maximize your living space with an ADU from Abodu

Ready to expand your property’s living potential? Abodu is your go-to partner.

When it comes to ADU versus JADU, the former is a clear winner if you want to make the most of your real estate.

Committed to providing a seamless customer experience, the Abodu team strives to craft a custom prefab ADU that aligns with your ideals and enhances your daily life.

Our tried-and-true approach to new ADU construction combines personalized attention with professional expertise. Let’s create a new chapter in your home's story.

Book a call or showroom tour today.

Contact Abodu to help you build your ADU in California.

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