Garage Conversion Contractors in Cupertino, CA

Cupertino allows an existing garage to be converted into an accessory dwelling unit (ADU), with no replacement parking required. A garage conversion counts as an ADU rather than a junior ADU, ADUs can be up to 850 square feet for a studio or one-bedroom and 1,000 square feet for two or more bedrooms, and ADUs under 750 square feet pay no city impact fees. Design by M&M designs, permits and builds garage conversions in Cupertino, from the first feasibility check through final inspection. We bring 22+ years of experience, 1,000+ completed projects and CSLB license #1082131.

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Garage Conversion Options in Cupertino

Many Cupertino neighborhoods are made up of single-story homes with an attached two-car garage, including Eichler tracts. With land prices high and lots already built out, the garage is often the most practical place to add a separate living unit for parents, adult children or long-term tenants, without building new square footage.

Garage to ADU

Cupertino allows existing garages to be converted into an ADU with its own kitchen, bathroom and entrance. One rule matters early in design: when a garage becomes an ADU, no part of that garage can be converted into living space for the main house at the same time.

Why a garage is not a JADU in Cupertino

The city treats a garage as an accessory use, not part of the main home, so a garage conversion is considered an ADU rather than a junior ADU. A JADU in Cupertino is created within the walls of the main home itself.

Garage to added living space

A garage can also become part of the main house, such as a bedroom suite or family room, instead of an ADU. This follows standard zoning and building rules, so we confirm floor area and parking during feasibility.

GARAGE CONVERSION

Cupertino Rules That Shape a Garage Conversion

State ADU law sets the baseline, and the City of Cupertino applies its own standards on top. These are the rules that matter most for a garage conversion:

Units per lot: a single-family lot can have up to three streamlined ADUs or JADUs, subject to the city’s standards for each type.
Size: 850 square feet for a studio or one-bedroom ADU and 1,000 square feet for two or more bedrooms.
Parking: no replacement parking is required when converting a garage into an ADU.
Separation: no internal access between the ADU and the main home is allowed, except for a JADU with a shared bathroom.
Fees: ADUs under 750 square feet do not pay city impact fees such as park or storm drain fees. School impact fees are set by the school district.
Rentals: ADUs can be rented but not sold separately, and ADUs and JADUs cannot be used as short-term rentals.
Address: a detached ADU must have its own address.

We confirm current requirements with the City of Cupertino before design is finalized. See California ADU laws every homeowner should know for the statewide rules.

The Cupertino Permit Process

Feasibility and preliminary review. We review the garage and lot, and Cupertino Planning accepts preliminary plans and questions by email before a formal submittal.
Building permit submittal. A building permit is required for every ADU. We prepare and submit the plans through the city’s Building Permit Center.
Plan review. Planning and Building review the plans for zoning and code compliance. If comments come back, we revise and resubmit.
Construction and inspections. The city inspects the work through final.

State law requires the city to act on a complete ADU application within 60 days. A complete first submittal is the best way to keep that clock moving. Read more about garage conversion permits in California.

What Makes Cupertino Garages Easier or Harder to Convert

Attached garages on single-story homes usually have short utility runs, which helps cost.
Full separation: because internal access to the main home is not allowed, the door between an attached garage and the house is typically closed off with a fire-rated wall.
Eichler homes use post-and-beam framing and radiant floors, so we plan the conversion carefully to respect the original design.
Older slabs often slope toward the door and lack a vapor barrier, so most conversions need a new level floor.
Electrical panels in older homes are often too small for a second unit and need an upgrade.

See is my garage a good candidate for conversion? for the full checklist, and what affects the cost of a garage conversion for budget planning.

How Long Does a Cupertino Garage Conversion Take?

Plan for three phases. Design and engineering come first. City plan review follows, and its length depends on the city and on how complete the first submission is. Construction typically takes 8 to 12 weeks once permits are issued, depending on the slab, structural and utility work. We give you a schedule for all three phases at the start, so you can plan around move-in or tenant dates.

Design by M&M handles design, engineering, permits and construction under one contract, so you work with one team from the first site visit to the final inspection. Learn more about our garage to ADU conversion services across the Bay Area.

Our Design-Build Process

Consult & Feasibility

We visit the garage, check the slab, panel, sewer and lot, and confirm what your city allows: ADU, JADU or added living space.

Design & Permits

Floor plans, 3D design previews and a detailed estimate, then structural and Title 24 drawings, submittal and plan check through permit issuance.

Build & Final Inspection

Our team builds the slab, framing, utilities, insulation and finishes, then closes out the permit with the city and walks you through the finished space.