Unlock New Space with Quality ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
The popularity of ADU construction has surged in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have encouraged 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 offers greater control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. When you're ready to explore what ADU construction could look like on your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction involves the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — 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 basement or interior conversions.
Mechanically, everything kicks off with a comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. 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. Components should be specified to match the primary home's aesthetic. 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 professional rigor we use on major custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction offers family members a private, independent living space without moving to another neighborhood.
- Customization Options — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of requiring new development, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans tailored to your needs. Space is thoughtfully allocated to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for review and approval. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are issued, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few clear categories. If you have a residential property with available square footage under zoning rules, 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.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since the long-term value is proven.
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. Brother & Brother Builders reviews each property on its own merits to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction more info generally falls between $150,000 to $400,000 or more for a detached new build. Interior conversion projects are generally priced lower, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be given after completing a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. 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 move out during ADU construction?
In most cases, you won't have to vacate your house during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the process. Exceptions may arise if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials is designed to last as long as the main residence — typically 50 years or more. How long it lasts comes down to the systems installed, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district frequently see their parcels work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. If you're located closer to Evergreen, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Book Your ADU Construction Consultation Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to fully independent secondary homes. The process begins with a comprehensive site assessment where we understand your vision and provide an honest assessment of what's achievable.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and help you take the next step. 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