Expand Your Home with Quality 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 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 see these visions to life with precision and integrity.
The interest in 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 add these secondary units, and local municipalities like San Jose have embraced 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 offers greater control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction describes the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the work starts with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. 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 completely finished living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected to match the primary home's aesthetic. Systems like HVAC and drainage 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
- Increased Property Value — ADU construction delivers real 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 self-contained residence without losing proximity to the family.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what can be built before any money is spent on design.
- Custom Design and Architectural Planning — Our design team create precise architectural drawings 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 review and approval. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished 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?
Homeowners who benefit most from ADU construction often belong to a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already well-positioned. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who runs a small business and wants a private work environment click here that doesn't interfere with your family's daily life. Real estate-minded homeowners who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and local permitting timelines. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction cost in San Jose?
Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection 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 the project's location on your property. Standalone ADU projects are typically less disruptive, 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. We provide advance notice about what to expect at each stage.
Do I need to move out during ADU construction?
For the majority of homeowners, you won't have to vacate your house during ADU construction. Most job sites are designed so that you remain on the property throughout the construction timeline. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight should last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use high-quality components and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road 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. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from kickoff through certificate of occupancy.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. We bring years of hands-on experience in ADU construction across a wide range of project types — from simple garage conversions to large custom detached cottages. Our approach opens with a thorough and honest property review where we listen to your goals and share clear expectations of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and make sure you feel confident before committing. Building an ADU is a major decision — 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