The Down-Low on a Special Kind of ADU: Junior Accessory Dwelling Units (JADUs)

This post originally appeared on MaxableSpace.com.

Have you heard of a Junior Accessory Dwelling Unit or “JADU”? Under California state law*, homeowners can now build BOTH an ADU and a JADU on their property! But what is a Junior ADU?

In short, JADUs follow these guidelines:

• Located within existing walls of primary residence, including within attached garage

• Owner occupies rest of house

• Maximum size 500 square feet

• Separate exterior entrance

• Efficiency kitchen: sink, cooking appliance, counter surface and storage

• May share a bathroom with primary residence

*Each local city and county creates its own different set of local rules for ADUs and JADUs. This blog post outlines the California state laws that govern those local rules. Great news: Local cities and counties can be more permissive than state law. Before making any decisions about a JADU for your property, make sure to check your specific local rules. These can be found at your local city or county website and will also be updated soon at our City Rules page.

The folks over at Maxable have put together a great blog post on JADUs, and we’re sharing the most relevant sections here:

You may think that accessory dwelling units already had enough names…. ADU, granny flat, in-law suite, casita, the list goes on… 

So what the heck is a JADU?

After the adoption of Assembly Bill No. 68 and Assembly Bill No. 881, homeowners are now allowed to add both an ADU and a JADU to their property. 

The definition of JADU was also updated to be more lenient. JADUs previously could only be created from the conversion of existing bedroom space. That’s not the case anymore. 

The folks at Modative put together a helpful definition of Junior Accessory Dwelling Units (JADU):

What is a JADU?

• Size – 500 sq. ft. max 

• Location – Must be within a proposed or existing single-family dwelling or accessory structure, such as a garage or carport. (According to California Department of Housing & Community Development the accessory structure, like a garage, must be attached to the home to qualify)

• Expansion – May include an expansion of up to 150 sq. ft. beyond the footprint of the existing accessory structure, but this expansion is limited to accommodating ingress and egress. With the expansion, your JADU still must maintain the less than 500 sq ft rule. 

• Separate Entry – Exterior access (a separate entrance for the JADU) is required from the proposed or existing single-family dwelling.

• Parking – No parking required for a JADU, except if you convert your attached garage, in which case the parking must be replaced.* 

• Bathroom – May have a separate bathroom or shared with the single-family dwelling.

• Kitchen – Must meet “Efficiency Kitchen” requirements:

  • The required kitchen sink (16”x16” max.) should have a small drain line (1.5” diameter max.)

  • No appliances that require natural or propane gas

  • A food preparation counter and storage cabinets that are of reasonable size in relation to the size of the JADU

  • Appliances that do not require electrical service greater than 120 volts

A JADU is a legally rentable unit.

So you can put an ADU and a JADU on the property and rent them both out. However, according to Section 65852.22. Section A, you’ll see that owner-occupancy is required for the JADU.

You may be thinking — well, wait! Owner Occupancy was banned from 2020-2025 under the new ADU laws. You’d be correct, except it only applies to ADUs, not JADUs.

Here’s where the owner-occupancy clause is broken out Section 65852.22

“(2) [JADUs] Require owner-occupancy in the single-family residence in which the junior accessory dwelling unit will be permitted. The owner may reside in either the remaining portion of the structure or the newly created junior accessory dwelling unit. Owner-occupancy shall not be required if the owner is another governmental agency, land trust, or housing organization.” 

That section goes on to talk about deed restriction, which will also apply to your ADU. 

(3) Require the recordation of a deed restriction, which shall run with the land, shall be filed with the permitting agency, and shall include both of the following:

(A) A prohibition on the sale of the junior accessory dwelling unit separate from the sale of the single-family residence, including a statement that the deed restriction may be enforced against future purchasers.

(B) A restriction on the size and attributes of the junior accessory dwelling unit that conforms with this section.

*Replacement Parking is Required for JADUs under state law, but many jurisdictions in Napa and Sonoma Counties don’t have this requirement.

Under state law, no jurisdiction can require replacement parking for a garage conversion to an ADU, but a JADU doesn’t get those same perks. If converting a garage to a JADU, the parking must be replaced. Check your local jurisdiction’s rules however, as local jurisdictions can have more lenient requirements. Regardless, if you’re converting space within the home, JADUs are exempt from all parking requirements!

Head back to the “Stories” section of our napasonomaadu.org website to check out a video of a neighbor in Sebastopol who built her JADU for $10,000.