Expand Your Home with Professional ADU Construction
Families in San Jose, CA are realizing 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 generate rental income. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with craftsmanship and integrity.
The demand for ADU construction has increased significantly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build 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 gives you more control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the aesthetic decisions that make an ADU functional. When you're ready to explore 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 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 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, the process begins with a detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like HVAC and drainage 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 Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what ADU types will work before any time is invested in drawings.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A closing municipal review issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few recognizable groups. If you have a residential property with available square footage under zoning rules, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who works from home and wants a private work environment that doesn't interfere with your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property individually and honestly 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 commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. City review on its own can take several months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while custom detached builds require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget 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 where the ADU is being built. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you are not required to vacate your primary residence during ADU construction. Most job sites are designed so that you stay in your primary unit throughout the process. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight should last as long as any standard residential structure — typically 50 years or more. How long it lasts comes down to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds click here use residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Residents in the Rose Garden district have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as housing demand rises. If you're located closer to Evergreen, our team has likely worked nearby.
Local regulatory bodies in this area applies particular standards for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from design through the final walkthrough.
Start 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 ready to guide you. Our builders provide licensed expertise in ADU construction including all types of project types — from modest studio builds to large custom detached cottages. Our approach opens with a comprehensive site assessment where we understand your vision and share clear expectations of what's achievable.
Contact Brother & Brother Builders to begin the conversation. Even if you're just exploring the idea, we enjoy discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632