Looking for more space in your main house? You may have heard of additions and ADUs. However, your backyard may be too small, house a colossal heritage tree, or its slope may make construction costs prohibitive.
Have you ever considered a Junior Accessory Dwelling Unit? If you have unused space inside the main home and you’re looking for a secondary unit of no more than 500 square feet, a JADU may be a great fit!
A junior ADU can house family members (like your mother-in-law) or be repurposed as your home office—it’s a secluded space, so it will offer enough privacy! You can also use your JADU to generate some extra rental income.
However, a Junior ADU and a regular ADU have some differences. Which one should you choose? Before you can make the decision, let’s look into the details of JADUs and learn all about them. Keep reading for your ultimate guide to Junior Accessory Dwelling Units!
You know those traditional ADUs—the units built in the backyard for additional living space. A junior accessory dwelling unit (a.k.a. JADU) is basically a smaller and more flexible version of that. It is, however, built within the existing footprint of your home. The JADU may be created within the walls of the proposed or existing single-family residence, including attached garages, as attached garages are considered within the walls of the existing single-family residence.
This means it is part of your primary residence. Think of a converted basement, attic, etc. The most frequently used conversion by real estate investors is a primary bedroom. Why? It already has an en suite bathroom! Just add a kitchenette, and you have a new rental unit.
A junior ADU would be between 150 and 500 square feet in size. Although this may seem extremely small, a Junior ADU is strategically planned so every square inch is used well! This may involve sharing some amenities with the primary home, such as the bathroom.
While the exact features depend on your state’s law, you can expect the following when building a Junior ADU in California.
Location: Built within the premises of your existing home. You can carve a JADU out of any unused space—an existing garage, basement attic, perhaps even a spare bedroom. However, it must be part of the primary dwelling unit. It cannot be converted out of the accessory structure.
Size: This can be a minimum of 150 square feet and a maximum size of 500 square feet.
Amenities: It has to be a self-contained living unit. One must-have amenity for a JADU is a kitchenette. This should be fully functional with a sink, counter space, and essential appliances (not requiring a range). A separate bathroom would be desirable. But even if you can’t fit it in the floor plan, that’s alright. Sharing with the main house will do – plan for an interior access in this case.
Entrance: Your JADU should have a separate entrance. This must be exterior (so you can enter from outside, not just from within the home). This ensures residents can independently access the space.
Parking: May be required.
Both units extend the livable space in your home. A permit application for an accessory or a junior accessory dwelling unit shall be considered and approved ministerially without discretionary review or a hearing within 60 days of receipt of a completed application.
Both will be considered residential units after the final inspection.
But what are the differences? Let’s find out!
Before building your JADU, it’s important to note that these definitions can vary for every state. Check your State law, plus other local ordinances created by governmental agencies. Different cities/counties can create their own local ordinances around JADUs. While they may conflict with our above definition, they follow the same idea.
Here are some questions to ask your local planner:
With so many definitions, knowing what you should follow can be tricky. To start—find out which jurisdiction you fall under. One way to do this is by looking at your address and city/county. Next, visit your local government’s website and read their guidelines for JADUs. You must follow the rules because you’ll be expending quite some effort!
If you cannot find local JADU regulations, contact your local planning department and speak to them directly.
So, why exactly should you build a Junior Accessory Dwelling Unit? It is one of the most affordable housing options. The effort brings plenty of benefits for you and your property, including—
JADUs are much cheaper to build ( compared to ADUs) because they utilize existing infrastructure. There is no need for separate utility connections. The permitting process is simplified, and building permit fees are also lower. There is no need for new construction—no new foundation, no soil haul-off. Impact fees may be waived entirely.
Adding a JADU increases the livable space in your home, increasing the property value of your single-family residence. Generally, an ADU can boost your property value by 30%.
If you have unused areas around your home, put them to good use with a Junior ADU. You can repurpose that empty room or garage into a home office, in-law suite, guest suite, etc. You do not have to worry about site setbacks.
If that complex permitting process puts you off, a JADU will give you a smooth process. Getting a permit will be much easier because you’re not opting for structural changes (in most cases). Plus, some jurisdictions don’t need building or fire code upgrades. That said, a fire-rated wall may be required between your main home and the junior unit.
Keeping loved ones nearby is a blessing, but privacy concerns are real! If you’re struggling with the same, a JADU will allow you to keep family members from several generations under the same roof. But with their own private living spaces!
If you plan to rent j ADU out (you want to check who is allowed to stay in the JADU in your county), you can also generate extra income. You can create a JADU in addition to an ADU. That means a triplex on your single-family residency without any change in zoning —and increasing rental income.
Building a Junior Accessory Dwelling Unit has all its benefits but has some limitations, too. These include:
You want to weigh these cons against the pros and decide what works for you.
To get started, prepare all the necessary documents, including a site and floor plans for the existing single-family dwelling. Use our ADU Planner as a guide.
Building permit applications must include the floor plan of the existing residence, often with some floor area calculations.
Consider your budget.
The cost to develop a Junior Accessory Dwelling Unit in your home can vary. The exact figure depends on the materials you use, the type of construction you’re willing to do, etc. But generally, a breakdown of costs will look like:
The amount you’ll be spending depends on the nature of your project. When deciding on the amount—be sure to factor in unexpected costs! The extra dollars used as a cushion can help avoid delays in your project.
You can expect to pay between $20,000 and $100,000 for a JADU. You’d need to be lucky to get the project done for $20,000. Think of a room with an ensuite bathroom and an exterior door that requires an efficiency kitchen and city fees paid. However, this is not the case for most people.
Here are some tips to save money while developing your JADU. First off, get quotes from multiple contractors. You want to compare prices (while keeping quality in mind) when you choose your contractor. When deciding on a layout, think about a simple one that will be easy to achieve. You also want to utilize existing infrastructure (instead of thinking of building/extending infrastructure). And if you’re handy—you can even take up some non-critical tasks to save labor costs.
Does a Junior Accessory Dwelling Unit sound like your thing? That’s great! Here are a few things to consider before you develop one.
Here are some ideas for you:
If a Junior Accessory Dwelling Unit suits you (and your family), go for it! It’s an investment that will really pay off in the long run. It will open new opportunities in terms of multigenerational living and rental income. Plus, it helps you utilize the space that would otherwise remain unutilized.
We are always on standby to give you a helping hand.
