ADU Builders in the Bay Area, CA
Custom ADU Design & Plans By Local Experts At Anura Design
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Full-Service ADU Design and Construction in the Bay Area
As ADU builders in the Bay Area, Anura Design takes a project from first sketch to final inspection. Everything happens under one roof: architectural design, structural and MEP engineering, permit submittals, and construction. Our office is in Pleasant Hill, in Contra Costa County, and we work with homeowners across the East Bay, the Peninsula, and the South Bay.
Most ADU projects involve at least three separate companies: a designer, an engineer, and a builder. Each handoff is a chance for drawings to fall out of sync and for the schedule to slip. We keep design and engineering on the same team, so the plan set that goes to your city is already coordinated.
Our ADU construction services in the Bay Area include:
- Feasibility studies and site analysis
- Architectural design and 3D visualization
- Structural, civil, and MEP engineering
- Full permit sets and submittal to your city or county building department
- Title 24 energy compliance documentation
- Construction and project management
Every project is designed for your specific lot and goals, not adapted from a generic plan.
Garage Conversion ADUs in the Bay Area
A garage conversion is the fastest and lowest-cost way to add an ADU in the Bay Area. The foundation, walls, and roof already exist, so the work is mostly interior framing, insulation, systems, and finishes. California law requires cities to allow garage conversion ADUs on most single-family lots, and it does not allow them to require replacement parking for the garage space you convert.
We handle the full conversion: new floor plan, egress windows, insulation and drywall, kitchen and bathroom rough-ins, electrical panel upgrades, and permits. Older Bay Area garages often need foundation and structural upgrades to meet code for living space. Our structural engineers assess that on the site visit, so there are no surprises after demolition starts.
Detached garages, attached garages, and tandem garages can all become ADUs or junior ADUs.
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Our team of architects, structural engineers, and project managers works together on one plan set, so your Bay Area ADU moves from feasibility to permit-ready drawings without the handoffs that slow most projects down.
Prefab and Pre-Approved ADU Plans in the Bay Area
Prefab ADUs and pre-approved plans can shorten your timeline, but they still need site-specific engineering and a city permit. A prefab unit arrives partly built, then gets set on a foundation that has to be designed for your soil and your lot.
Several Bay Area cities, including San Jose, offer pre-approved ADU plan programs that speed up plan review for the building itself. Even with a pre-approved plan, you still need a site plan, a foundation design, utility connections, and any grading or drainage review your city requires.
Anura Design prepares that site-specific package for prefab and pre-approved ADUs, and we can build the foundation and complete the connections. If you are comparing a prefab unit to a custom build, we can price both options during the feasibility stage so you can see the real cost and timeline difference.
Detached, Attached, and Junior ADUs: Which One Fits Your Property
The right ADU type depends on your lot size, your budget, and how you plan to use the space.
- Detached ADU (DADU): a standalone unit in the backyard. Best for rental income, family members, or a home office with privacy. Most flexible, highest cost.
- Attached ADU: an addition connected to the main house. Good when the yard is small or you want interior access.
- Junior ADU (JADU): up to 500 square feet, created within the existing walls of the house, often from a bedroom or attached garage. Lowest cost, but it can share a bathroom with the main home.
- Garage conversion ADU: covered in its own section above, a middle path on cost and effort.
We help you compare these during feasibility, using your actual lot dimensions, setbacks, and utility locations.
Bay Area ADU Permits and Zoning
Every Bay Area city and county runs its own ADU permit process, but California’s ADU law sets the ground rules for all of them. State law requires your city to approve or deny a complete ADU application within 60 days, and it overrides most local restrictions, which is why most single-family and multifamily lots in the Bay Area can add at least one ADU.
Key rules that shape a Bay Area ADU design:
- Size: cities must allow a detached ADU of at least 850 sq ft (one bedroom) or 1,000 sq ft (two or more bedrooms), and many allow up to 1,200 sq ft. JADUs are capped at 500 sq ft.
- Setbacks: cities cannot require more than 4-foot side and rear setbacks for a new ADU
- Height: generally 16 to 25 feet, depending on the ADU type, the lot, and nearby transit
- Parking: no replacement parking for garage conversions, and parking is waived within half a mile of public transit
- Owner-occupancy: not required for a standard ADU under current state law
Hillside lots, fire hazard zones, historic districts, and coastal areas can carry extra review. We confirm which of those apply to your address during the feasibility study, before any design work starts. Local rules change, so we verify current requirements with your city for every project.
Finding the Right ADU Contractor in the Bay Area
The best ADU contractors in the Bay Area do three things: they check feasibility honestly before you pay for design, they keep engineering in-house or tightly coordinated, and they give you a real permit-set price up front. A lot of ADU projects stall because the design and the engineering were done by separate firms that never talked to each other.
Anura Design keeps architects and structural engineers on the same team, working from one model. We are rated 5.0 stars across 16 Google reviews, and we also hold reviews on Yelp, Houzz, and BuildZoom. Our license and insurance details are on our license page, and we are happy to share references for completed ADU and addition projects.
Still comparing options? Our guide to the best ADU companies in the Bay Area covers what to look for and how local builders compare.
Our ADU Design and Build Process
Every Anura ADU project follows the same six steps, so you always know what comes next.
- Feasibility: we review your lot, zoning, and utilities and give you a cost range and a realistic timeline
- Design: floor plans, elevations, and 3D views, revised with you until the layout is right
- Engineering: structural, civil, and MEP engineering integrated into the same drawing set
- Permitting: we prepare the full submittal and manage plan check with your city or county
- Construction: our team builds the ADU, with one project manager as your point of contact
- Final inspection and closeout: sign-off, utility connections, and handover
Building in the South Bay? See our page for ADU builders in San Jose. If you would rather expand the main house, we also design Bay Area home additions. Outside Northern California, Anura works as ADU builders in Los Angeles and designs ADUs in Seattle.
Frequently Asked Questions About ADUs in the Bay Area
How long does it take to build an ADU in the Bay Area?
Most ADU projects take about 9 to 14 months from first meeting to final inspection. Design and engineering take 2 to 3 months, permitting takes 2 to 4 months depending on your city, and construction takes 4 to 7 months depending on the ADU type. Garage conversions and pre-approved plans are usually on the shorter end.
How big can an ADU be in the Bay Area?
State law requires cities to allow a detached ADU of at least 850 square feet for one bedroom or 1,000 square feet for two or more, and many Bay Area cities allow up to 1,200 square feet. A junior ADU is capped at 500 square feet and must be created within the existing house.
Do I need a permit for an ADU in the Bay Area?
Yes. Every ADU needs a building permit from your city or county, including garage conversions and prefab units. State law requires the city to act on a complete application within 60 days.
Can I build an ADU and a junior ADU on the same lot?
In most cases, yes. California law generally allows a single-family lot to have one ADU plus one junior ADU. We confirm what your specific lot allows during the feasibility study.
Do I have to live on the property to build an ADU?
No. Owner-occupancy is not required for a standard ADU under current California law. A junior ADU is different: the owner generally must live in either the main house or the JADU.
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