Brother & Brother Builders

Transform Your Property with Professional ADU Construction

Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to 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 precision and integrity.

The popularity of ADU construction has surged in recent years, and it's easy to understand 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 increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property functions.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the design choices 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 the ADU Construction Process?

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 — equipped with 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 basement or interior conversions.

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 local building department. 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 fully functional living unit attached to or separate from your main home.

What separates excellent ADU construction from an average project is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains 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.
• Space for Loved Ones — ADU construction gives aging parents a private, independent living space 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 barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Sustainable Land Use — Building an ADU uses your existing lot instead of expanding urban sprawl, which supports broader sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• 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 evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any time is invested in drawings.
2. Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Layouts are carefully considered to optimize daily use.
3. Permit Submission and Municipal Review — 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, responding to review feedback promptly.
4. Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This includes grading the site, laying the structural base, and running initial plumbing and electrical conduits.
5. Structural Framing and Weatherproofing — Framing is completed followed by weatherproofing and exterior finish materials. This phase, the ADU takes its visible shape.
6. MEP Systems Rough-In — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Every system is reviewed at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A closing municipal review grants legal occupancy status 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 have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners hoping to get more info offset mortgage costs through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.

Another strong candidate is someone who works from home and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who already own residential properties are also a natural fit for ADU construction, since the return on investment is well-documented.

Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may face additional constraints. Brother & Brother Builders reviews 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 complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. Permitting alone can take a significant portion of the overall timeline in San Jose, so starting early is important. 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?

Budget requirements differ based on whether it's a conversion or new construction. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions are generally priced lower, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a formal feasibility evaluation.

Is ADU construction intrusive while it's underway?

The day-to-day impact depends on the project's location on your property. 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 move out during ADU construction?

In most cases, you do not need to vacate your primary residence during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will walk you through any potential disruptions during the pre-construction consultation.

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

An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Our builds use high-quality components and comply with all local building codes to deliver a structure that stands the test of time.

ADU Construction for Local Homeowners

Residential areas across San Jose present a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. 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.

Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means smoother project delivery from kickoff through certificate of occupancy.

Book Your ADU Construction Consultation Today

When you want to add an ADU to your property, Brother & Brother Builders is here to help. We bring years of hands-on experience in ADU construction for many different project types — from small attached additions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.

Reach out to our team to begin the conversation. Whether you're in the early stages of planning, we enjoy answer questions, share examples of our work and give you the clarity you need to move forward. Building an ADU is a major decision — and we're committed to helping you get it right.

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