Your garage,
a small home.

Start with one question: is the garage legal?

Only a legal structure can be converted as a conversion ADU. To the City, that means a building built with permits, or one old enough to predate the need for them. In the County, an illegal structure can still become an ADU, but it is treated as new construction, with the requirements that come with that. If the garage was already turned into a room without permits, the County and the City both run programs to legalize older unpermitted units.

Parking

• County. Converting a garage to an ADU doesn't require replacing the lost parking, except in the County's designated coastal areas: in Live Oak; in Seacliff, Aptos and La Selva; in Davenport and Swanton; and on Opal Cliff Drive between 41st Avenue and Capitola. There, replacement parking is required.
• City of Santa Cruz. Outside the Coastal Zone, parking removed for an ADU doesn't have to be replaced. Inside it, the rules depend on the location.

How big it can be

A conversion ADU has no maximum size in either the City or the County. The County sets a minimum of 150 square feet. In the City, you can expand the building by up to 150 square feet of footprint and up to 2 feet of height. Under the state's short list of standards, an expansion of a detached garage beyond its walls is limited to what's needed for getting in and out.

The building code

This is where a garage conversion is decided. A garage was built to park cars, and the City says the converted building has to meet today's building code for a home. The County lists what a conversion ADU must include:

• a full bathroom,
• a full kitchen,
• its own entrance,
• its own heat source, and
• sound and fire separation from the main house, if it's attached.

The County's advice is to have a contractor look at the condition of the garage first, to see whether converting it makes more sense than building new.

Fees and utilities

• County. Conversion ADUs get reduced building permit fees, and the County waives its sewer and water connection fees for them.
• City of Santa Cruz. A conversion doesn't need its own water and sewer connections, but it can outgrow the existing water meter. Upsizing the meter can mean opening the street, so the City recommends talking to its Water Department early.
• Fire sprinklers. The City can't require sprinklers in an ADU when the house doesn't have or need them.

What our conversions have cost

Historically, our garage conversions have come in around $320,000, against around $400,000 for a new studio.

What we look at on a site walk

When Warren Swanepoel, the owner of WS Builders, walks a garage, he's looking at the things that decide the price: the slab and foundation, the walls and roof, the ceiling height, how far the sewer and water lines are, where the electrical panel is, and how a front door and windows will fit. You get a fixed price in writing before any work starts.

Making a garage feel like a home

A garage is one open box, which helps. The rooms that work best keep the kitchen, dining and living space together, put storage into the walls rather than the floor, and add windows and a glass door where the garage door was, for light. We design every conversion in house, so the layout and the permit drawings are done by the same team that builds it.

Questions homeowners ask

Do I have to replace the parking if I convert my garage?

Usually not. In the County you don't, except in its designated coastal areas, which include parts of Live Oak, Seacliff, Aptos and La Selva. In the City of Santa Cruz you don't outside the Coastal Zone.

Can I make the garage bigger when I convert it?

In the City, by up to 150 square feet of footprint and 2 feet of height. The added space has to meet the setback and height standards for new ADUs.

What if my garage was built without a permit?

The County treats it as new construction, which brings more requirements. If it was built as a unit before 2020, the County and the City both have programs to legalize it.

Is a garage conversion cheaper than building new?

Usually. The City and County both say a new detached unit is the most expensive kind of ADU. Historically, our garage conversions have come in around $320,000, against around $400,000 for a new studio.

Sources

1. ADU Basic Requirements (legal structures, conversion size, parking, fee waivers), County of Santa Cruz
2. Plan Your Financing (conversion ADUs and garage conversions), County of Santa Cruz
3. Senate Bill 13 program for unpermitted ADUs, County of Santa Cruz
4. Accessory Dwelling Units (conversion standards, parking, water, sprinklers), City of Santa Cruz
5. ADU Legalization, City of Santa Cruz
6. Typical totals: WS Builders' own ADU projects in Santa Cruz County.

Rules change. We checked every source on October 27, 2026. Call the City or County planning counter before you design.