Our specialty
Accessory Dwelling Units
Every ADU we build is custom, designed around your lot and built from the ground up on site. We do not sell modular or prefab models. We work alongside architects and designers from the first feasibility conversation through the final walkthrough, and we have completed them at every size from a 400-square-foot hilltop studio to a 1,200-square-foot home with an office and walk-in closet.
Types we build
Detached ADU
A separate structure in the yard, with its own kitchen, bath, and entrance. The majority of what we build.
Attached ADU / addition
Built onto the existing house, sharing a wall while keeping a private entrance and full independence.
Converted existing space
A garage, basement, or underused portion of the house brought up to code as a full dwelling unit.
JADU
A junior ADU carved out of the existing footprint — the smallest and usually the fastest route to a second unit.
Start here
Talk it through with us
Tell us where the property is and what you have in mind. We will tell you honestly whether it works.
Contact Us Or call (510) 617-8559Licensed in CaliforniaCSLB #1085381B — General Building
Where we work
Richmond · El Cerrito · Albany · Pinole · Hercules · Berkeley · Emeryville · Oakland · Piedmont · Alameda · San Leandro · Orinda · Moraga · Lafayette · Walnut Creek · Pleasant Hill · Concord · Martinez · Alamo · Danville · San Ramon · Dublin · Pleasanton · Livermore · Castro Valley · Hayward · Fremont · San Francisco · Marin County
See where we have builtHow it works
From first walk to final walkthrough
01
Feasibility
We walk the property with you and, together with the architects we build with, work out whether an ADU pencils on your lot and which type fits it. Lot size, setbacks, slope, access, and where the utilities run all shape the answer.
You bring: The address, and any survey or existing plans you already have.
02
Design
We work alongside your architect or designer from the first drawing, or introduce you to ones we build with regularly. Having the builder at the table early means what gets drawn is what can actually be built to budget.
You bring: How you plan to use the space: a rental, room for family, a home office.
03
Permits
Plans, structural engineering, and the city review, coordinated by us. Requirements and review cycles differ from city to city across the East Bay, and we have taken ADUs through several of them.
You bring: Sign-off on the plan set, and any owner forms the city requires.
04
Build
One team on site from foundation to final walkthrough. Change orders are explained before the work happens, not after, and Gilbert stays closely involved on site throughout.
You bring: Finish decisions, made on a schedule we set together.
From our projects
Custom ADUs we have built
Cost
What moves the price
Every ADU is priced to its lot, so we do not publish a per-square-foot number. Two units of the same size can land far apart. What we can tell you is what moves the price, and how we quote it.
Site access
A level lot with a clear path to the backyard is the simplest case. Hillsides, long carries from the street, and tight side yards add labor and equipment. Several of our ADUs sit well up a slope, so we account for this from the first walk.
Foundation and soil
Slope and soil decide between a standard slab and step-down foundations or drilled piers. It is often the largest single swing in a budget.
Utility connections
How far the new unit sits from the existing sewer, water, gas, and electrical service, and whether the main panel needs an upgrade to carry a second home.
Size and type
A garage conversion or junior unit reuses a structure that already exists. A detached ADU starts from the ground up.
Finish level
Cabinetry, stone, windows, and fixtures. Much of our work is architect-designed with custom millwork, and the finish schedule is where you have the most control over cost.
How we quote and bill
An itemized quote before you commit, payments tied to defined milestones, and change orders discussed before the work begins. Several clients mention this in their reviews.
Clients
In their own words
“We used GR for our 400sq ft. ADU - they were great from start to finish, even with foundation and electric challenges that we had to overcome. All of their subcontractors are also hard workers. GR listened to any concerns we had and were open to changes we wanted from the original designs. We are grateful to have worked with them and recommend them.”
Rena
Lafayette, CA · 400 sq ft ADU
“We chose GR Innovative Builders to build an ADU in our backyard in Berkeley and we could not be happier! Gilbert and Marlyn are a fantastic team. They patiently answered a million questions I had as we went along and I always felt like they were going above and beyond to make sure I was happy with the build. Billing was clear, with no surprises, and all of the subcontractors seemed excellent (I could write odes about the tiler!). Gilbert clearly cares about what he does and about the quality of the work and the final result is beautiful. I'm already scheming about what other remodeling projects I can have them work on.”
Kelly
Berkeley, CA · Backyard ADU
“We recently had the pleasure of working with GR Innovative on the construction of our ADU (Accessory Dwelling Unit), and the experience was nothing short of excellent.”
Kenneth Woo
Google review
“We selected GR Innovative to build our ADU. It was a difficult project because the access was up a hill, quite a distance from the road. Gilbert and his team were amazing, the quality of their work exceeded our expectations and Gilbert’s attention to detail is admirable. Gilbert and his team were on top of the project the entire time – he was onsite and communicative about each step of the project. He has a great team and special shout out to Marlene and Claudia - (Chief of Staff / Assistant) who are responsive, available and and patient to answer all my questions! I love how they handled the quote and billing – it was concise and clear, and payments were clearly defined. The team is very professional, left everything clean and were respectful of our neighbors. We felt like the team is honest, forthright in what was going on, and fair. My husband and I highly recommend GR Innovative and are extremely happy with our ADU.”
Jeanette
Dublin, CA · Hillside ADU
“We had a fantastic experience working with GR Innovative Builders, Inc. on both our ADU construction and full home renovation. From start to finish, the team was professional, thoughtful, and incredibly easy to work with.”
Vadim Alden
Google review
“We were so pleased with Gilbert, Marlyn and the team who completed our backyard ADU this past year.”
Nicole Callis
Google review
Questions
Custom ADUs, answered
All four: detached ADUs (a separate structure in the yard), attached ADUs built onto the house, conversions of a garage or basement, and junior ADUs carved out of the existing home. Most of our work is detached, and we have built them from a 400-square-foot hilltop studio up to a 1,200-square-foot home with an office and walk-in closet.
That is the first thing we work out, before anyone commits to a design. We walk the property and, with the architects we build with, look at lot size, setbacks, slope, access, and where the utilities run. If an ADU will not pencil on your lot, we will tell you.
A junior ADU (JADU) is created inside the existing home, often from a bedroom or an attached garage, and California caps it at 500 square feet. It has its own entrance and a small kitchen, and can share a bathroom with the main house. A full ADU is larger and fully independent, with its own kitchen, bath, and entrance. A JADU is usually the smallest and fastest route to a second unit.
It depends on the lot more than the square footage. Site access, foundation and soil, utility connections, size and type, and finish level all move the number, which is why we do not publish a per-square-foot price. We walk the property and give you an itemized quote.
Most of our ADUs take about four to seven months to build. Where a project lands in that range depends on its size and type, site access, and the finish schedule. Design and city permitting come before that and run on their own timeline, which varies from city to city across the East Bay.
An itemized quote before you commit, payments tied to defined milestones, and change orders explained before the work happens, not after. Several clients mention this in their reviews.
No. Every ADU we build is custom, designed for your lot and built from the ground up on site. There is no catalog of models to choose from; the design starts with your property and how you plan to use the space.
Yes. Most of our ADUs are architect-designed, and we are glad to build from your architect's plans. If you do not have one, we can introduce you to designers we build with regularly. Bringing the builder in during design keeps the drawings buildable and on budget. You contract with the architect directly, and we stay involved through design.
Often, yes. When a past client is up for it, we can arrange a visit to one of our finished ADUs. Ask about it when you get in touch.
Yes. Several of our ADUs sit on hillsides with long carries up from the road. Step-down foundations, drilled piers, and tight-access logistics are routine work for us.
We coordinate the plans, structural engineering, and the city review. Requirements and review times vary from city to city across the East Bay, and we have taken ADUs through several of them.
Across the East Bay, including Lafayette, Berkeley, Oakland, Alameda, Walnut Creek, and Danville, as well as San Francisco.
See where we have builtAlso