Garage Conversion Contractors in Mountain View, CA
Mountain View allows a garage to be converted into an accessory dwelling unit (ADU), a junior ADU or added living space. No planning permit is needed for an ADU, state law does not allow the city to require replacement parking when a garage becomes an ADU, and the city estimates building permit fees of $3,000 to $5,000 for converting existing space. Design by M&M designs, permits and builds garage conversions in Mountain View, 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 Mountain View
Many Mountain View homes sit on compact lots where a new backyard cottage would take most of the yard. The garage is often the largest space on the property that is not used as living space. Converting it can create a rental unit near major employers, a home for parents or adult children, or extra room for your own household, without building new square footage.
Garage to ADU
An attached or detached garage can become a full home with its own kitchen, bathroom and entrance. Mountain View allows ADUs of up to 850 square feet for a studio or one-bedroom and 1,000 square feet for two or more bedrooms. An attached ADU cannot exceed 50% of the main home’s floor area.
Garage to junior ADU
A junior ADU of up to 500 square feet must be contained entirely within the walls of the home. Mountain View requires that either the home or the JADU be occupied by an owner, and a deed restriction must be recorded before the JADU building permit is issued.
Garage to added living space
A garage can also become part of the main house, such as a bedroom suite or family room. This follows standard zoning and building rules rather than the ADU rules, so we confirm floor area and parking during feasibility.
Mountain View Rules That Shape a Garage Conversion
State ADU law sets the baseline, and the City of Mountain View applies its own standards on top. These are the rules that matter most for a garage conversion:
- No replacement parking for a garage ADU
- No owner occupancy required for an ADU
- JADUs up to 500 sq ft with a deed restriction
- 60-day decision on a complete application
- Approval: no planning permit is required. The project needs a building permit and a demolition permit, plus excavation or fire sprinkler permits if they apply.
- Size: 850 square feet for a studio or one-bedroom ADU, 1,000 square feet for two or more bedrooms, and 500 square feet for a JADU.
- Setbacks: state law lets an existing garage be converted in place without meeting new setbacks. Any added square footage must meet the city’s 4-foot side and rear setbacks.
- Parking: state law prevents the city from requiring replacement parking when a garage is converted to an ADU. JADUs need no parking.
- Fees: the city estimates $3,000 to $5,000 in building permit fees for converting existing space to an ADU. School impact fees apply to new residential space over 500 square feet, including conversions, and must be paid before the permit is issued.
- Ordinance status: in May 2026 the state housing department told Mountain View its ADU ordinance may be out of date with state law. Where the two conflict, state ADU law applies.
We confirm current requirements with the city before design is finalized. Read more about ADU construction in Mountain View.
The Mountain View Permit Process
- Feasibility and optional planning check. We review the garage and lot, and can confirm zoning compliance with a city planner before detailed drawings, which can streamline building review.
- Submittal. We submit one PDF plan set with structural and energy calculations, an electrical load calculation, the Green Building worksheet, a title report or grant deed, and a Change of Address Request Form. A site survey is needed if the structure is within 6 feet of a property line or setback.
- Prescreen, fees and plan check. The city prescreens the submittal, collects fees and starts plan check. Each review cycle takes about two weeks.
- Permit issuance. Proof of school impact fee payment is required before the building permit is issued.
- Construction and inspections. Inspections are scheduled online, and the permit is finaled after the last inspection.
The city says a typical ADU permit takes 4 to 6 months to receive. A complete first submittal is the best way to avoid extra review cycles.
Read more about garage conversion permits in California.
What Makes Mountain View Garages Easier or Harder to Convert
- Attached garages usually have short utility runs, which helps cost.
- Electrical capacity: the city requires an electrical load calculation, and many older panels need an upgrade to carry a second unit.
- Older slabs often slope toward the door and lack a vapor barrier, so most conversions need a new level floor.
- Ceiling height can drop below the minimum once the floor is leveled and the ceiling insulated, so we measure before design.
- Construction waste: Mountain View requires a construction and demolition waste tracking account, which we set up as part of the permit.
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 Mountain View 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.
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Frequently Asked Questions
If you don’t see your question answered here, please don’t hesitate to contact us directly – we’re always happy to help.