Transform Your Property with Expert ADU Construction
Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates 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 skill and integrity.
The interest in ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater 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 requirements, and the design choices that make an ADU beautiful. If you've been thinking about what ADU construction could look like on your property, this guide covers 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 — featuring a kitchen, bathroom, sleeping area, and its own entrance — 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 work starts with a comprehensive review of your lot, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable 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 private, independent living space without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints tailored to your needs. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are issued, the build starts. This includes grading the site, laying the structural base, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. 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 clear categories. If you are a homeowner with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
Another strong candidate is someone who works from home and wants a private work environment that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities 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 typically take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Straightforward interior conversions may complete more quickly, while custom detached builds take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a standalone website backyard unit. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be developed after a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during certain phases of construction. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you do not need to vacate your main home during ADU construction. Most job sites are set up to let 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. Our construction supervisors will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU should last as long as any standard residential structure — indefinitely with proper upkeep. How long it lasts comes down to the systems installed, how consistently minor repairs are addressed, and how proactively issues are resolved over time. Brother & Brother Builders specifies high-quality components and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road have seen growing ADU activity as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our familiarity with these local conditions means fewer surprises from design through the final walkthrough.
Start Your ADU Construction Consultation Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction including all types of project types — from simple garage conversions to fully independent secondary homes. Every project starts with a detailed, no-pressure consultation where we listen to your goals and share clear expectations of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and help you take the next step. 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