Highland, CA Accessory Structures: Garage Conversions (2026)

Garage conversions in the City of Highland run through the accessory dwelling unit section, Highland Municipal Code § 16.44.180, not through a separate garage ordinance. The rule that matters most to owners is the parking one. The general requirement is one off-street parking space for each ADU in addition to the spaces required for the primary dwelling. But when the ADU is created by converting or demolishing a garage, carport, covered parking structure, or uncovered parking space, replacement of the parking spaces eliminated by the construction is not required, so long as the ADU remains in use as a legal ADU.

The one-space requirement also falls away in listed situations, including an ADU within one-half mile walking distance of public transit, one within an architecturally and historically significant historic district, one that is part of a proposed or existing primary dwelling or accessory structure, one in an area where on-street parking permits are required but not offered to an ADU occupant, and one within one block of a city-approved and dedicated car share parking space. Where parking is provided, it can sit in setback areas in locations determined by the planning division, or be tandem.

The building-permit-only route in subsection E covers conversions of existing space. It applies to an ADU or JADU within the existing space of a single-family dwelling or accessory structure, with an expansion of not more than 150 square feet beyond the existing accessory structure, limited to ingress and egress. The space must have exterior access from the dwelling, and side and rear setbacks must be sufficient for fire and safety. For a JADU, enclosed uses within the residence such as attached garages are considered within the walls of the single-family dwelling, and a separate exterior entry is required.

In a multifamily building, garages are among the non-livable spaces that can be converted: the number of ADUs equals 25 percent of the existing units or one ADU, whichever is greater. All conversions must satisfy the California Building Standards Code as amended by the city, and the owner must get a building permit and any other applicable construction permits before construction.