Transform Your Property with Professional ADU Construction
Homeowners across 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 flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and transparency.
The popularity of ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering considerations, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could do for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction involves the process of designing, permitting, and building 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 comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the work starts website with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the local building department. Once permits are secured, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional 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. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we use on major custom home projects.
Key Benefits 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 can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Sustainable Land Use — 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 delivers a genuinely independent unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any time is invested in drawings.
- Custom Design and Architectural Planning — Licensed architects and designers create detailed floor plans tailored to your needs. Space is thoughtfully allocated to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. Every system is reviewed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. A final city inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who needs a dedicated professional workspace 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 rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Brother & Brother Builders reviews each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally 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 how quickly approvals come through. The approval phase alone can take two to four months in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while custom detached builds require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. Locally, ADU construction commonly costs $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. A detailed estimate can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the build. Certain situations could require a brief departure 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 last?
An ADU constructed with quality materials is designed to last as long as the main residence — typically 50 years or more. How long it lasts comes down to the systems installed, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components 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. Residents in the Rose Garden district have found their lots work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units 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 follows defined procedures for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our team's knowledge of the San Jose permitting environment means fewer surprises from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our builders provide proven skills in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and give you a realistic picture of what's achievable.
Get in touch with our office to schedule a site visit. Whether you're in the early stages of planning, we enjoy answer questions, share examples of our work and make sure you feel confident before committing. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632