An ADU, or Accessory Dwelling Unit, serves as an accessory to the primary home structure. It can take the form of an attachment to the main residence, a conversion of an existing space, or the construction of a new detached unit. In California, ADUs are required to encompass areas designated for living, sleeping, cooking, and bathroom facilities. Essentially, they must be fully functional and habitable structures.

ADUs are gaining popularity among homeowners as a means to boost property value, extend living spaces, foster proximity to friends and family, and generate potential income through both long and short-term rentals. Furthermore, their compact size and relatively modest pricing make them an attractive alternative to purchasing existing single-family homes, particularly in states like California. In California, the state has provided incentives for homeowners to incorporate ADUs into their properties, aiming to enhance population density without imposing substantial alterations to the neighborhood's character—a common concern associated with the construction of multifamily properties.