Expand Your Home with Expert ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with skill and integrity.
The demand for ADU construction has increased significantly in here recent years, and it's no mystery. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property serves your household.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — including a kitchen, bathroom, sleeping area, and its own access point — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the work starts with a detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we bring to full custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — 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 offers family members a comfortable home of their own without losing proximity to the family.
- Customization Options — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Streamlined Approval Process — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of requiring new development, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU holds its value 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 determine what type of ADU is allowed and where it can be placed. This phase answers exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints tailored to your needs. Layouts are carefully considered to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are granted, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Landlords and real estate investors who are building a portfolio 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. Parcels in historic districts or HOA-restricted communities may need a modified approach. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction cost in San Jose?
Costs vary widely based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during specific stages like framing or MEP rough-in. We provide advance notice about what to expect at each stage.
Do I need to leave my home during ADU construction?
Generally speaking, you do not need to vacate your main home during ADU construction. Most builds are structured to allow you stay in your primary unit throughout the process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials is designed to last as long as your primary home — typically 50 years or more. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are well suited for ADU construction. Property owners near the Almaden Valley area have found their lots accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. 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 applies particular standards for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our familiarity with the San Jose permitting environment means smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a thorough and honest property review where we listen to your goals and give you a realistic picture of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. Building an ADU is a major decision — 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