Expand Your Home with Professional ADU Construction
Families in more info 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 flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and transparency.
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 add 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 functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the design choices that make an ADU functional. When you're ready to explore what ADU construction could look like on your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
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 self-contained living space — featuring a kitchen, bathroom, sleeping area, and its own access point — 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, the process begins with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once permits are secured, 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.
What sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same professional rigor we bring to full custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a comfortable home of their own without leaving the property.
- Design Flexibility — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of requiring new development, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
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 stage clarifies exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Our design team create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose involves filing drawings 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, the build starts. This includes grading the site, completing foundation work, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A final city inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. 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 works from home and wants a separate office or studio space 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 sites with unusual utility access challenges. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. The approval phase 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 can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be produced following a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are typically less disruptive, 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. Brother & Brother Builders keeps you informed 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 primary residence during ADU construction. Most job sites are designed so that you remain on the property throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios 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 the main residence — typically 50 years or more. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. Our builds use high-quality components and build to current California residential standards to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. 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. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our team's knowledge of this region's building landscape means smoother project delivery from the first meeting to the final inspection.
Start Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide years of hands-on experience in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture of what the project will involve.
Get in touch with our office to begin the conversation. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects 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