A JADU (Junior Accessory Dwelling Unit) is a specific type of accessory dwelling unit (ADU) in California. It is a small, self-contained living unit that is created within an existing single-family home. The main distinction between a JADU and other types of ADUs is that a JADU is created within the existing space of the primary residence, typically by converting a part of the house, such as a bedroom or a portion of the living area.

Key characteristics of a JADU include:

1. Size Limit: A JADU must not exceed 500 square feet in California.
2. Entrance: It must have a separate entrance from the main residence. This entrance can be through an exterior door or an entrance from within the house that does not require passing through the primary dwelling’s interior.
3. Facilities: A JADU includes a kitchenette (small kitchen) and bathroom facilities for independent living.
4. Owner-Occupancy: One of the unique features of a JADU is that the owner of the primary residence must live on the property. This means that the property owner needs to reside in either the primary residence or the JADU.
5. Permitting Requirements: Like other ADUs, a JADU typically requires building permits and must comply with local building codes and zoning regulations.

The purpose of a JADU is to provide additional housing options for extended family members, caregivers, or renters while utilizing the existing space in single-family homes efficiently. JADUs can be beneficial in increasing the supply of affordable housing and addressing the housing shortage in California. Keep in mind that regulations and laws may vary depending on the specific city or county, so it is essential to check with local authorities to ensure compliance with all requirements.