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ADU Architect & Design Services in the Bay Area
Hamilton Exteriors provides ADU architect and design services. We plan the site, floor plan, exterior, 3D views, engineering coordination, and permit documents before construction begins. Serving the Bay Area and Northern California.
500+ projects
Since 2018
Limited Lifetime
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ADU design begins with the buildable part of the property. We map setbacks, access, slope, trees, utilities, privacy, sunlight, and the main home's windows before setting the footprint.
Compact ADU plans need clear priorities. Storage, daylight, door swings, furniture, kitchen clearances, bathroom access, and mechanical equipment all compete for space. We test those choices in measured plans rather than forcing rooms into a stock layout.
A useful ADU design resolves conflicts before permit drawings are complete. We check furniture clearance, storage, windows, structure, energy details, and utility routes against the same measured plan. That review gives the homeowner a clear layout while the design is still practical to revise.
How We Design an ADU
The design moves from property facts to a coordinated permit package.
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Document the Property
We review the lot, existing home, setbacks, access, utilities, trees, slope, privacy, and available property records.
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Develop the ADU Design
We test the footprint, floor plan, exterior, windows, storage, and building systems. Plans and 3D views support clear design decisions.
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Prepare the Permit Package
Architecture, structural engineering, energy documents, and site information come together in one coordinated submission set.
ADU Design Deliverables
| Stage | What You Review | Output |
|---|---|---|
| Site study | Placement, setbacks, access, utilities, and privacy | Feasibility plan |
| Concept design | Room layout, size, and exterior direction | Design options |
| Design development | Windows, materials, systems, and details | Coordinated design |
| Permit documents | Final plans and consultant work | Agency submission set |
Fit the ADU to the Lot
Placement affects privacy, yard use, construction access, and utility cost. We study the available footprint and the main home's windows, outdoor areas, and circulation. The plan should create a useful ADU without making the rest of the property harder to use.
Make a Small Floor Plan Work
Compact rooms need clear priorities. Storage can use full-height cabinets and built-ins. Wet rooms can share plumbing walls. Door locations can protect furniture space. Windows can add daylight without reducing privacy. Each choice should improve daily use.
See the Design Before Construction
Plans communicate dimensions. Three-dimensional views communicate space. We use both so you can review ceiling height, exterior form, windows, furniture, and the ADU's position on the lot before the permit set is complete.
ADU Design Financing Options
ADU design costs can include the site study, architecture, 3D views, engineering coordination, energy documents, and permit plans. For eligible design-build projects, financing is available with approved credit and may cover qualified design and construction costs. Standalone design work may not qualify. During your consultation, we explain available terms and eligible project costs.
Ask whether your ADU design-build project qualifies for financing.
Call Now (650) 977-3351 ADU Design Reviews
Homeowner feedback from ADU design and construction projects.
Yaku Escobar
via Google
We worked with Hamilton Exteriors to build a small ADU in our backyard. from the beginning the process felt organized and clear. Alex Lee was very responsive and always kept us in the loop, especially during planning and inspections. The crew was consistent and respectful of the space which we appreciated since we were living there during the build. overall everything moved pretty smoothly and the final result looks exactly like what we had in mind. really happy with how it turned out.
Rafa Simons
via Google
My family hired Hamilton after seeing the neigbours new ADU, the whole team were super organized and tecnological and also very patient to undestand my needs before starting the construction. But what i like the best is that they are really preocupated with the final result and they kept us well inform with details and everything. Definitely recomend them.
Kevin L
via Google
We hired them for a bigger renovation. Alex was very responsive, which I appreciated. We changed a couple requirements during the job and they worked with us on it without making it complicated. Overall, everything went pretty smooth and their quality of work is solid. I recommend them highly!
Jacob Rothwell
via Google
Alex Li helped me with my basement remodeling, they were super efficient, and the work came out better than I could’ve ever imagined! Thank me later!
Frequently Asked Questions
Didn't find the answer to your question? Call Now (650) 977-3351
Do I need an architect for an ADU?
The required design professionals depend on the site, structure, and local review. Complex sites, custom layouts, and structural changes can need licensed design oversight. We confirm the required documents and professional stamps during feasibility.
What does an ADU design package include?
A typical package includes a site plan, floor plans, elevations, building sections, roof plan, key electrical and plumbing layouts, structural coordination, energy documents, and permit details. The exact set follows the project and local agency requirements.
How long does ADU design take?
A typical design takes six to eight weeks before agency review. Site complexity, survey needs, client revisions, structural work, and utility planning can change that timeline.
How do you test the ADU layout before construction?
We use measured floor plans, elevations, and 3D views. These show room sizes, furniture clearances, window placement, exterior form, and the ADU's relationship to the house and yard.
Can you use a city pre-approved ADU plan?
We first compare the plan with your lot, access, utilities, privacy needs, and local program rules. A pre-approved plan can shorten part of the review, but the site plan, foundation, utilities, and project-specific documents still need coordination.
What information starts the ADU design process?
We need the property address, intended use, target size, room needs, budget range, and known site records. A survey, title report, utility information, or prior plans can help when available.
Get Your ADU Design Quote
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