Expert ADU Construction Services for Homeowners

Expand Your Home with Quality ADU Construction

Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides 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 precision and care.

The demand for ADU construction has grown rapidly in recent years, and it's not hard to see 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. 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 bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide will walk you through 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 — featuring a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property as a primary residence. ADU construction can take several forms, 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 relevant municipal authority. Once permits are secured, ADU construction enters the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit adjacent to or detached from your main home.

What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor 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.
• Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
• Housing for Extended Family — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
• Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
• Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, resulting in a timeline 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 produces a fully self-contained unit where occupants have full privacy.
• Durable Return on Investment — A well-built ADU holds its value for the long haul by offering both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Site Evaluation and Zoning Analysis — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any time is invested in drawings.
2. Blueprint Development and Layout Design — Our design team create precise architectural drawings tailored to your needs. Layouts are carefully considered to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
4. Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This covers land preparation, completing foundation work, and establishing utility connections.
5. Shell Construction and Exterior Finishing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
6. Interior Systems and Infrastructure — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at required milestones throughout ADU construction.
7. Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.

Who Is a Strong Candidate for ADU Construction?

Homeowners who benefit most from ADU construction typically fall into a few common profiles. 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 accommodating adult children who need housing.

You may also be someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.

Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Brother & Brother Builders reviews each property individually and honestly to advise you on what's feasible.

ADU Construction Common Questions Answered

How long does ADU construction usually take from start to finish?

The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and how quickly approvals come through. City review on its own can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units may complete more quickly, while larger new construction ADUs take longer to complete.

What does ADU construction usually run in terms of budget?

Budget requirements differ 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 fully custom construction. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be developed after 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 generally the least intrusive, since the construction zone is separate. Projects that connect to the main structure may require temporary access during key milestones. We provide advance notice about what to expect at each stage.

Do I need to move out during ADU construction?

Generally speaking, you are not required to vacate your house during ADU construction. The vast majority of projects are designed so that you continue living in the home throughout the construction timeline. There are edge cases if major utility upgrades affect the main house in ways that require short-term access disruption. Our construction supervisors will flag these situations during the planning phase.

How long will an ADU built through professional ADU construction hold up?

A well-built ADU can be expected to last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, how well routine maintenance website is performed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies commercial-grade materials and follow all code requirements to protect your investment for the long haul.

ADU Construction for San Jose Homeowners

San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Residents in the Rose Garden district have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. Whether your property is near downtown San Jose, our team has project experience in the area.

San Jose's permitting office follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from the first meeting to the final inspection.

Schedule Your ADU Construction Assessment 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 small attached additions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what's achievable.

Get in touch with our office to begin the conversation. Even if you're just exploring the idea, we're glad to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. ADU construction is a significant investment — and our goal is to ensure it delivers real value.

Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632