An ADU (formally known as an Accessory Dwelling Unit) refers to an auxiliary housing unit built in addition to the primary dwelling unit. ADUs comply with local and state requirements to be considered true dwelling units rather than supplementary structures. This key distinction allows for lawful habitation of the unit meaning they can legally be occupied and / or rented.
In 2017 California adopted statewide legislation making ADUs legal in all cities in an effort to help address the State’s affordable housing crisis. California has since continued to encourage ADU development though the passage of subsequent ordinances making it easier than ever to build an ADU. These additional housing units are expected to increase the overall rental supply statewide in turn easing the current rental supply / demand imbalance.
ADU eligibility and specific building requirements vary by city / county. However, generally speaking the majority of residentially zoned lots (single family homes and multifamily properties) are allowed at least 1 ADU. As part of our consultation process, we will assess your property’s ADU feasibility to ensure you are fully aware of your ADU building opportunities.
There are two main classifications of Accessory Dwelling Units: ADUs and JADUs (Junior Accessory Dwelling Units).
Having outlined what an ADU is (see question 1 if you need a refresher), we can focus on JADUs.
JADUs were adopted as part of California’s AB 2406 allowing local governments to permit a second classification of accessory dwelling unit. JADUs can often be built in addition to an ADU and have a separate set of standards required to be considered a JADU rather than an ADU. Notably, JADUs have a 500 square foot size limit and must be contained within the existing envelope (existing space) of the primary dwelling unit. Because of the latter requirement, many JADUs are either converted garages or bedrooms that offer independent living space from the primary dwelling unit. While a garage or bedroom conversion does not HAVE to be considered a JADU rather than ADU, if the space meets JADU requirements (outline and comparison below), it is certainly an excellent option to consider in order to maximize your home’s ADU count.
| Requirements | ADU | JADU |
| Maximum Unit Size | 800sf by right, many jurisdictions allow up to 1,200sf | 500sf |
| Kitchen | Standard Kitchen Required | Standard or “Efficiency” Kitchen Allowed |
| Bathroom | Independent Bathroom Required | Independent Bathroom or Common Sanitation Allowed |
| Parking | Depends, Parking May Be Eliminated and Cannot Be Required Under Specific Conditions | No Parking Requirement |
| Owner Occupancy | Depends, Owner Occupancy May be required (often times not) | Yes, Owner Occupancy is Required |
| Ministerial (“By Right”) Approval | Yes, local agencies must allow for ADU development subject to building requirements and standards | Yes, local agencies must allow for JADU development subject to building requirements and standards |
Within these two main classifications of accessory dwelling units, there are multiple build types. These include but are not limited to:
- Detached ADUs: Construction that develops a dwelling unit that shares no common walls with the existing primary dwelling unit (think back house, granny flats, backyard cottages, in-law house, or even converting a detached garage space to a living unit.) This can either be new, “ground-up” construction or conversion of an existing detached structure. Because these create new space rather than renovate the existing primary dwelling unit envelope, detached ADUs are not eligible to function as JADUs.
- Attached ADUs: Any accessory dwelling unit that is attached to or created from the existing primary dwelling unit. Examples include:
- Attached garage conversions
- Basement conversions
- Bed / living room conversions
- Home additions
Because these are all attached to the primary dwelling unit, these types of ADU developments can be eligible to function as a JADU assuming they meet other JADU requirements.
To have a legal accessory dwelling unit that can lawfully be inhabited and / or rented, the unit must be fully permitted. In addition to managing the entire construction process, ADU Builder LA handles all permitting requirements on behalf of its clients.
- ADUs are an affordable development type because they do not require paying for land or major infrastructure improvements.
- ADUs can increase your property’s value by adding square footage and providing a rental unit that can generate rental income to offset or cover your mortgage payments.
- ADUs give families the flexibility to be near one another while maintaining privacy and independence – perfect for college students, young adults, aging family members and more!
- ADUs can provide much needed space for a variety of different uses. From business owners that want a home office, creators looking for a studio, and growing families that don’t want to move, ADUs present a straightforward and cost-effective solution to give you the additional square footage you need.