Unlock New Space with Professional ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with skill and integrity.
The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of engineering, filing for, and completing 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 access point — that is located on the same parcel as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins 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 city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders treats each project with the same professional rigor we bring to full custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of consuming open land, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what ADU types will work before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create detailed floor plans based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
- 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, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This includes grading the site, completing foundation work, and establishing utility connections.
- Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
- MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A last official inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction often belong to a few common profiles. If you are a homeowner with available square footage under zoning rules, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who works from home and wants a detached creative or business space that doesn't interfere with your family's daily life. Property investors and rental owners who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property on its own merits to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while custom detached builds take longer to complete.
What does ADU construction cost in San Jose?
Costs vary widely based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you do not need to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you remain on the property throughout the construction timeline. Certain situations could more info require a brief departure if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials can be expected to last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select high-quality components and comply with all local building codes to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. The Berryessa area are seeing more homeowners add secondary units as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that our team navigates routinely. Proximity to transit corridors can impact the design approach for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means smoother project delivery from the first meeting to the final inspection.
Book 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. Our experts offer licensed expertise in ADU construction across a wide range of project types — from modest studio builds to large custom detached cottages. The process begins with a comprehensive site assessment where we listen to your goals and share clear expectations of what's achievable.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632