Transform Your Property with Professional ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a powerful new living space on your existing website property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with craftsmanship and care.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering considerations, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a comprehensive review of your lot, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders treats each project with the same technical discipline we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a comfortable home of their own without losing proximity to the family.
- Customization Options — From open-plan one-bedrooms, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any money is spent on design.
- Custom Design and Architectural Planning — Licensed architects and designers create comprehensive blueprints tailored to your needs. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. We manage this entire process on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A final city inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few clear categories. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who needs a dedicated professional workspace and wants a detached creative or business space that remains away from your family's daily life. Landlords and real estate investors who already own residential properties are also well suited for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our experts will evaluate each property case by case to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take several months in San Jose, so planning ahead matters. Smaller detached units can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be given after completing a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as the main residence — typically 50 years or more. How long it lasts comes down to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area often discover their properties accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office has developed specific protocols for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our team's knowledge of these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Consultation Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. We bring years of hands-on experience in ADU construction across a wide range of project types — from small attached additions to multi-room backyard residences. The process begins with a comprehensive site assessment where we understand your vision and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, our team is happy to walk through your options, review completed projects and give you the clarity you need to move forward. ADU construction is a significant investment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632