Unlock New Space with Professional ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest 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 helped hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported 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 offers greater control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the aesthetic decisions that make an ADU functional. 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 describes the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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, everything kicks off with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from 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 align with the neighborhood's character. Systems like wiring and water supply 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 Advantages ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction provides adult children a comfortable home of their own without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction is adaptable to your specific needs.
- Streamlined Approval Process — Recent state legislation has reduced the permitting obstacles 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 requiring new development, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Space is thoughtfully allocated to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, physical construction begins. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A last official inspection confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction typically fall into 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 navigating multigenerational living situations.
You may also be someone who runs a small business and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who already adu construction CA own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property on its own merits to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take a significant portion of the overall timeline in San Jose, so starting early is important. Simpler garage conversions often finish in the lower end of the range, while multi-room detached cottages require more time.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors based on project complexity and finishes selected. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a formal feasibility evaluation.
Is ADU construction intrusive 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 construction zone is separate. Interior conversions may involve some shared wall work during key milestones. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
In most cases, you do not need to vacate your house during ADU construction. The vast majority of projects are designed so that you continue living in the home throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that require short-term access disruption. Our construction supervisors will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU can be expected to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a diverse mix of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as housing demand rises. Whether your property is near downtown San Jose, our team has likely worked nearby.
Local regulatory bodies in this area applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction for many different project types — from simple garage conversions to large custom detached cottages. Every project starts with a comprehensive site assessment where we listen to your goals and provide an honest assessment of what's achievable.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. 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