Unlock New Space with Professional ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical 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 precision and care.
The popularity of ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. Whether you're building 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 apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering considerations, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction refers to 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 access point — 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 comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction moves into the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — 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 provides adult children a comfortable home of their own without losing proximity to the family.
- Customization Options — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive 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 delivers a genuinely independent unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU holds its value for the long haul by offering both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what ADU types will work before any money is spent on design.
- Custom Design and Architectural Planning — Licensed architects and designers create comprehensive blueprints based on your goals. Space is thoughtfully allocated to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and establishing utility connections.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review issues the certificate of occupancy and your new space is cleared 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 hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who runs a small business and wants a detached creative or business space that remains away from your family's daily life. Property investors and rental owners who are building a portfolio are also a natural fit for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Our team can assess each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. Permitting alone can take several months in San Jose, so planning ahead matters. Straightforward interior conversions can move faster, while custom detached builds require more time.
What does ADU construction typically cost?
Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on the project's location on your property. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home 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 process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight can be expected to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties work click here well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team has likely worked nearby.
San Jose's permitting office has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit corridors 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 the first meeting to the final inspection.
Book Your ADU Construction Consultation Today
When you want to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to schedule a site visit. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632