09/29/2026
Most Bay Area homeowners considering a garage ADU tend to lead with the same question: "What's this going to cost me?"
The straightforward answer is that the garage structure itself is rarely where the budget climbs. The real variables are everything that surrounds it.
Here are a few of the cost factors we talk through with homeowners early on:
Utility connections. A garage was built to park cars, not house people. Bringing in water, sewer, gas, and electricity often means extending or upgrading existing lines from the main home. Electrical panel capacity is one of the more common things that catches people off guard.
Structural and seismic considerations. Many older garages across the Bay Area, particularly detached ones, require foundation work, shear wall additions, or other structural improvements before they can meet the requirements for legal living space.
Insulation, egress windows, and Title 24 compliance. Converting a storage structure into a habitable unit means meeting energy codes, ventilation standards, proper egress, and fire separation requirements when the garage shares a wall with the main home.
Site specifics. Grade changes, setback requirements, drainage patterns, and the distance between the garage and existing utility connections all influence what the project actually involves.
Design and permitting. Every city and county in the Bay Area has its own requirements, and the scope of work needs to be clearly defined before a meaningful budget can be developed.
The wide range you see in ADU conversion estimates comes down to this: many of the real cost factors only become visible once someone physically looks at the structure and the property. An estimate put together before that walkthrough is informed speculation. One built after it reflects what the project will actually take.
At Atlantis Remodeling, we approach garage-to-ADU work as a full-service general contractor, covering architectural design, permitting support, construction, and final completion. In that first conversation, our focus is not on pitching a number. It is on helping you understand what your garage, your lot, and your city's requirements will realistically involve, so the budget you move forward with is one grounded in your actual project.
If you are thinking about a garage conversion for rental income, a family member, or added flexibility in how you use your home, we are glad to walk the property with you and talk through it honestly.
Schedule a Free Consultation: (650) 376-7944
Which part of the ADU process feels least clear to you right now, the costs, the permitting side, or what construction actually looks like day to day?