Unlock New Space with Professional ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides 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 has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. When you're ready to explore what ADU construction could mean for your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction describes the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — 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 basement or interior conversions.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction moves into the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — 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 may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction offers family members a comfortable home of their own without losing proximity to the family.
- Personalized Layouts — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU holds its value for decades, providing both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are granted, on-site work kicks off. This includes grading the site, completing foundation work, and setting up utilities.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A last official inspection 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 typically fall into a few common profiles. If you own a single-family home with available square footage under zoning rules, you're already a strong candidate. Homeowners looking to generate income through rental are among the most common 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 is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property case by case to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for read more ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and local permitting timelines. Permitting alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions may complete more quickly, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Interior conversions may create short-term inconveniences during specific stages like framing or MEP rough-in. We provide advance notice about upcoming work and timelines.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your house during ADU construction. Most builds are structured to allow you continue living in the home 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 walk you through any potential disruptions during the planning phase.
How long will an ADU built through professional ADU construction last?
A well-built ADU should last as long as any standard residential structure — indefinitely with proper upkeep. Durability depends to the systems installed, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Our builds use residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. 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. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our team's knowledge of these local conditions means smoother project delivery from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
When you want to move forward with ADU construction, Brother & Brother Builders is the team to call. Our builders provide years of hands-on experience in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Reach out to our team to schedule a site visit. Even if you're just exploring the idea, 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632