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

what is a junior accessory dwelling unit

In the constantly changing real estate, traditional residences are making room for inventive housing alternatives. One such revolution comes in the form of accessory dwelling units (ADUs), offering homeowners the opportunity to expand their living spaces and generate passive income. However, for those seeking a more compact alternative, the junior accessory dwelling unit (JADU) emerges as a viable option. In this article, we delve into the intricacies of JADUs, exploring what sets them apart from their larger counterparts, ADUs.

What is a junior accessory dwelling unit?

A junior accessory dwelling unit, referred to as JADU, is a self-contained living area constructed within or connected to the primary residence. Commonly known as “in-laws” or “granny flats,” JADUs represent scaled-down alternatives to conventional ADUs. The key characteristic of a JADU is its limited size, typically capped at 500 square feet.

Unlike the standalone nature of ADUs, JADUs share utilities with the primary residence, including bathrooms and kitchens. This shared configuration sets them apart as connected units, created to offer extra living areas for family members, tenants, or visitors. JADUs present an economical option for those looking to increase their living space without the expense of constructing a completely independent structure.

How does it compare to an accessory dwelling unit?

To understand the distinctions between JADUs and ADUs, it’s essential to first grasp the concept of an accessory dwelling unit. An ADU is an independent living structure that can be installed adjacent to the primary residence but is not physically connected to it. Unlike JADUs, ADUs can be detached, offering more flexibility in terms of placement 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 noteworthy difference is in the usage. ADUs can be utilized for short-term rentals, providing homeowners with the option to engage in activities like Airbnb. On the contrary, JADUs are not permitted for short-term rentals, restricting their use to long-term contracts.


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

An important distinction is the owner’s occupancy requirement. JADUs can only be built on owner-occupied properties, meaning that the homeowner must reside in either the JADU or the primary home. ADUs, due to a 2022 California law, do not have owner-occupancy requirements, providing more flexibility for renting out both ADUs and main houses.

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?

Indeed, homeowners have the legal flexibility to incorporate both an ADU and a JADU on their property, creating a unique and multifaceted living arrangement. This arrangement can be particularly advantageous for those with diverse needs and goals.

Benefits of having both ADU and JADU

Versatility in Living Arrangements

The combination of ADU and JADU provides homeowners with versatile options for living arrangements. The main house, along with the attached or detached JADU, can cater to immediate family needs, while the standalone ADU offers independence for guests or additional rental income.

Income Generation

The presence of both ADU and JADU allows homeowners to maximize their income potential. The ADU, with its potential for short-term rentals, can cater to tourists or temporary residents, while the JADU provides a more permanent housing solution for long-term tenants.

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

In conclusion, the choice between a JADU and an ADU is contingent on various factors. Homeowners should consider their budget, space requirements, and long-term goals when deciding which option aligns best with their needs. Consulting local ordinances and regulations is crucial to ensure compliance with zoning laws and to streamline the permitting process.

As real estate continues to evolve, the emergence of JADUs as a practical and affordable living solution provides homeowners with additional options for expanding and enhancing their living spaces. Whether it’s the independent charm of an ADU or the budget-friendly appeal of a JADU, these accessory dwelling units offer innovative approaches to modern living.


  • 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.

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