Brother & Brother Builders

Expand Your Home with Expert 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 opens the door to 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 care.

The popularity of ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has simplified the process 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're building 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 apply deep hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.

What Is ADU Construction?

ADU construction describes 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 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 interior space reconfigurations.

Mechanically, the process begins with a comprehensive review of your lot, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit connected to or independent of your main home.

What sets quality ADU construction apart is the depth of planning at every stage. Components should be specified 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 apply to large-scale custom home projects.

Key Benefits ADU Construction

• Higher Resale Potential — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
• Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
• Housing for Extended Family — ADU construction gives aging parents a comfortable home of their own without leaving the property.
• Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
• Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which supports broader sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
• Long-Term Investment Security — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.

The ADU Construction Process Step by Step

1. Site Evaluation and Zoning Analysis — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what ADU types will work before any time is invested in drawings.
2. Blueprint Development and Layout Design — Licensed architects and designers create detailed floor plans based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
3. Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
4. Ground Prep and Structural Base — Once permits are approved, the build starts. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
5. Shell Construction and Exterior Finishing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
6. MEP Systems Rough-In — Certified technicians 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. Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to the approved plan. A last official inspection issues the certificate of occupancy and the ADU is ready for use.

Who Is a Right Fit for ADU Construction?

Property owners who are best suited from ADU construction typically fall into a few clear categories. If you own a single-family home 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.

ADU construction also suits someone who needs a dedicated professional website workspace and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.

Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may face additional constraints. Our team can assess each property individually and honestly to provide realistic options.

ADU Construction Common Questions Answered

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

The complete duration for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built 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. Straightforward interior conversions often finish in the lower end of the range, while larger new construction ADUs take longer to complete.

What does ADU construction typically cost?

Pricing depends on many factors based on project complexity and finishes selected. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects are generally priced lower, sometimes between $75,000 and $140,000. An accurate budget can only be developed after a thorough property review.

Is ADU construction difficult to live through while it's underway?

The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. Our team communicates clearly about any phases that may affect your routine.

Do I need to move out during ADU construction?

Generally speaking, you won't have to vacate your main home during ADU construction. Most builds are structured to allow you stay in your primary unit throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that require short-term access disruption. The team at Brother & Brother Builders will walk you through any potential disruptions during the kickoff meeting.

How long will an ADU built through professional ADU construction remain in good condition?

Any ADU built to code with professional oversight is designed to last as long as your primary home — indefinitely with proper upkeep. Durability depends to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Our builds use commercial-grade materials and build to current California residential standards to protect your investment for the long haul.

ADU Construction for Local Homeowners

The communities throughout San Jose provide a wide range of property types that are ideally positioned 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 families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.

The City of San Jose's building department follows defined procedures for ADU construction that our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means smoother project delivery from the first meeting to the final inspection.

Schedule Your ADU Construction Planning Session Today

Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our builders provide licensed expertise in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. The process begins with a comprehensive site assessment where we understand your vision and share clear expectations of what the project will involve.

Reach out to our team to begin the conversation. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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