Savvy Tips Guru

What Is Junior Accessory Dwelling Unit & Is It Worth Building?

what is a junior accessory dwelling unit

A junior accessory dwelling unit, or JADU, is like a small apartment built inside or attached to the main house. People often call them “in-law units” or “granny flats.” JADUs are smaller versions of regular ADUs (accessory dwelling units). One main thing about JADUs is that they’re usually no bigger than 500 square feet.

Unlike regular ADUs, JADUs share things like bathrooms and kitchens with the main house. This means they’re connected to the main house, not separate buildings. They’re made to give extra living space for family members, renters, or guests. JADUs are a cheaper way to add more space to a house without building a whole new building.

How does it compare to an accessory dwelling unit?

To see the differences between JADUs and ADUs, it’s important to know what an accessory dwelling unit is. An ADU is like a separate house that can be built next to the main home but isn’t connected to it. Unlike JADUs, ADUs can be completely separate, giving more options for where they can be placed on the property.


One of the primary differences lies in size. While ADUs can span over 1,000 square feet, JADUs are limited to a more compact 500 square feet. This size discrepancy reflects the intended purpose of JADUs as more modest living spaces.


Another important difference is how they can be used. ADUs can be rented out for short periods, like on Airbnb. But JADUs can’t be used for short-term rentals. They’re only allowed for long-term rental agreements.


ADUs can stand independently on a property, offering a separate living space. In contrast, JADUs must be attached to the primary residence, reinforcing their role as an extension of the existing home rather than a standalone unit.

Owner Occupancy

Another key difference is who can build them. JADUs are only allowed on properties where the owner lives, meaning the homeowner must live in either the JADU or the main house. But for ADUs, there’s a law from 2022 in California that says you don’t have to live on the property to build one. This gives more flexibility for renting out both ADUs and the main house.

What are the pros and cons of an ADU and a JADU?

Pros of ADUs

  • Size and Independence: ADUs offer more significant living space, making them suitable for families or those desiring a standalone residence.
  • Short-Term Rentals: The ability to use ADUs for short-term rentals opens up the possibility of additional income through platforms like Airbnb.
  • Flexibility: ADUs can be placed in various locations on the property, providing flexibility in design and utilization.

Cons of ADUs

  • Cost: Constructing a standalone ADU can be more expensive due to the need for additional utilities and amenities.
  • Space Requirements: ADUs may require more space on the property, limiting their feasibility for smaller lots.

Pros of JADUs

  • Affordability: JADUs are more economical to build, making them a budget-friendly option for expanding living space.
  • Shared Utilities: Sharing amenities with the main house reduces construction costs and simplifies renovation plans.

Cons of JADUs

  • Size Limitations: The limited size of JADUs may be a drawback for those seeking more spacious living arrangements.
  • Attachment Requirement: Being attached to the main house restricts the placement options for JADUs.

Is it better to get a JADU or an ADU?

The decision between opting for a Junior Accessory Dwelling Unit (JADU) or an Accessory Dwelling Unit (ADU) hinges on various factors, each carrying its own set of advantages and considerations.

Factors Influencing the Choice 

Budget Considerations

  • JADU: If budget constraints are a primary concern, JADUs offer a more economical solution. Their smaller size and shared utilities with the main house contribute to reduced construction costs.
  • ADU: While ADUs may come with a higher initial cost due to their standalone nature and additional amenities, they also present opportunities for generating income through short-term rentals.

Space Requirements

  • JADU: Homeowners with limited space may find JADUs to be a practical choice, given their compact size and attachment to the main house. This makes them suitable for properties with smaller lots.
  • ADU: For those with larger properties, ADUs provide the advantage of more significant living space and greater flexibility in terms of design and placement.

Independence and Flexibility

  • JADU: Homeowners seeking a seamless expansion of their existing living space, especially for accommodating family members or generating rental income, may appreciate the simplicity and shared amenities of a JADU.
  • ADU: Individuals desiring a more independent and standalone living arrangement, with the potential for short-term rentals on platforms like Airbnb, may find ADUs to be a better fit.

Long-Term Goals

  • JADU: JADUs are well-suited for those with immediate needs for additional living space without the need for significant independence. They serve as a cost-effective solution for both short- and long-term goals.
  • ADU: Homeowners with long-term goals of maximizing rental income and property value may lean towards ADUs. The versatility of ADUs makes them adaptable to various uses, including home offices or guest houses.

Can you get both of them?

Absolutely, homeowners have the legal freedom to include both an ADU and a JADU on their property, making for a versatile and varied living setup. This setup can be especially beneficial for people with different requirements and plans.

Benefits of having both ADU and JADU

Versatility in Living Arrangements

Having both an ADU and a JADU gives homeowners flexible choices for living situations. The main house, along with the attached or detached JADU, can be used for family members. Meanwhile, the separate ADU can provide independence for guests or extra money from renting it out.

Income Generation

Having both an ADU and a JADU lets homeowners make the most of their income opportunities. The ADU, which can be rented out short-term, can be great for tourists or people staying temporarily. Meanwhile, the JADU offers a more stable housing option for long-term renters.

Legal Requirements

It’s crucial to be aware of the legal stipulations that come with having both ADU and JADU. State laws generally require the homeowner to reside in the main house, ensuring that the property maintains a primary residence status.

Enhanced Property Value

The combination of ADU and JADU can significantly enhance the overall property value. The diverse living options and income potential contribute to a more attractive and lucrative real estate investment.

Getting JADU or ADU depends on several factors

Choosing between a JADU and an ADU depends on different things. Homeowners need to think about their budget, how much space they need, and what they want in the long run to figure out which one is best for them. It’s also important to check local rules and laws to make sure everything’s allowed and to make getting permission easier.

As real estate changes, JADUs are becoming a useful and affordable option for homeowners who want more space. Whether it’s the independence of an ADU or the budget-friendliness of a JADU, these extra living units offer new ways to live in the modern world.


  • RJ Sinclair

    RJ is our resident money guru, with a knack for keeping finances neat and organized. With previous experience as a budget manager in supply chain companies, he brings a wealth of knowledge and expertise to the table. Count on RJ as a trustworthy source for valuable money tips and advice to help you make the most of your financial journey.