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Detached Guest House Builder in the Bay Area
Hamilton Exteriors is a guest house builder. We plan and build the detached space: site design, utilities, engineering, permits, and final inspection. Serving the Bay Area and Northern California.
500+ projects
Since 2018
Limited Lifetime
Product Warranty
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We'll call within 3–5 minutes to schedule your consultation.
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Contractor credentials
Customer-Service Obsessed
Responsive from consultation through project closeout
Architect and general contractor
One accountable team
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Verified business credentials
A detached guest house creates private living space without changing the main home's floor plan. It can serve family, a caregiver, long-term guests, or a home office. The proposed use determines how the building should be designed and permitted.
The project starts with the site. Setbacks, buildable area, access, trees, slope, fire separation, privacy, and utility routes affect the building location and cost. We review those conditions before setting the footprint or choosing a floor plan.
A detached guest house can fit on paper and still fail at the utility route or construction access. We test sewer depth, electrical capacity, trench paths, equipment access, and the building footprint together. That keeps a practical site constraint from forcing a late floor-plan change.
How We Plan and Build a Guest House
Site conditions and intended use shape the building before construction begins.
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Test the Site
We review buildable area, access, trees, slope, privacy, fire conditions, utility routes, and the intended use of the detached space.
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Design and Permit the Guest House
The plans coordinate the footprint, rooms, foundation, exterior, structural work, energy documents, utilities, and local permit requirements.
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Build and Connect the New Home
Construction follows the approved set through site work, utility connections, the building shell, interior finishes, inspections, and closeout.
Guest House Site Review
| Item | What We Review | Why It Matters |
|---|---|---|
| Buildable area | Setbacks, lot coverage, easements, and trees | Sets location and size |
| Access | Crew, equipment, material, and emergency access | Shapes site work and schedule |
| Utilities | Water, sewer, electrical, and data routes | Affects layout and cost |
| Privacy | Windows, entries, paths, and outdoor areas | Supports both homes |
| Site rules | Fire, energy, drainage, and local permit needs | Sets the permit design |
Start With the Property
A standard floor plan cannot solve every lot. We measure the usable area, note utility points and trees, and study how people will reach the building. That information sets a practical location before the rooms and exterior take shape.
Design for Privacy and Daily Use
Window placement, entry direction, paths, lighting, storage, and outdoor space affect both the guest house and main home. We plan these relationships together so each building has useful light and privacy without wasting the yard.
Use One Team Through Final Inspection
Site work, utilities, architecture, engineering, permits, and construction are connected. A utility route can move the building. A setback can change the floor plan. One team tracks these decisions from feasibility through final inspection.
Guest House Financing Options
Guest house costs can include site design, architecture, engineering, permits, utility work, the foundation, and construction. Financing is available with approved credit for eligible project costs. During your consultation, we explain available terms, payment timing, and which parts of your guest house project can be financed.
Ask about guest house financing during your consultation.
Call Now (650) 977-3351 Guest House Reviews
Homeowner feedback from ADU and remodeling 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
Is a guest house the same as a detached ADU?
Not always. A detached building with its own cooking, sleeping, and bathroom facilities is commonly reviewed as an ADU. We confirm the permit classification from the intended use and local requirements before design starts.
Can a guest house include a kitchen and bathroom?
Yes, when the approved building type allows them. A detached ADU includes permanent cooking, sleeping, and bathroom facilities. Other accessory structures can have different limits. We define the use before design starts.
How do utilities reach a detached guest house?
The design can extend water, sewer, electrical, and data from the main property services. Distance, grade, panel capacity, sewer depth, and trench access affect the route and cost.
How much does a guest house cost?
Our current planning range is $350 to $600 per square foot. Size, site access, utility distance, foundation type, finishes, fire requirements, and permit conditions affect the final price.
How much site access does guest house construction need?
Access needs depend on the foundation, excavation, utility work, and material delivery. We map the path for crews and equipment during feasibility. Tight access can change the construction method, schedule, and cost.
Can the guest house match the main home?
Yes. We can coordinate roof form, windows, cladding, trim, and color with the main home. The design can also use a related style when an exact match would limit the guest house layout or site placement.
Get Your Guest House Quote
Tell us about your project. We usually call within 3–5 minutes.
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