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 rewarding investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and integrity.
The demand for ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier 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. If you're planning 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 draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. 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 an ADU Build?
ADU construction involves 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 — including a kitchen, bathroom, sleeping area, and its own access point — 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 interior space reconfigurations.
Mechanically, everything kicks off with a thorough property evaluation, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit attached to or separate from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Materials must be selected to complement the existing structure. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored 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.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any time is invested in drawings.
- Blueprint Development and Layout Design — Our design team create comprehensive blueprints tailored to your needs. Every square foot is planned to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- 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 designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few common profiles. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already well-positioned. 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 runs a small business and wants a private work environment that is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. Permitting alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on the type and size of the ADU. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions are generally priced lower, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a formal feasibility evaluation.
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. Standalone ADU projects are generally the least intrusive, since the crew operates at a distance from your living areas. 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 leave my home during ADU construction?
In most cases, you are not required to here vacate your house during ADU construction. The vast majority of projects are structured to allow you continue living in the home 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 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 your primary home — often several decades with routine maintenance. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Our builds use residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction for many different project types — from small attached additions to large custom detached cottages. Every project starts 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 schedule a site visit. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and help you take the next step. This type of project is a meaningful commitment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632