Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with skill and integrity.
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 construct these secondary units, and local municipalities like San Jose have encouraged 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 functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU functional. 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 involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — 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 process begins with a thorough property evaluation, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we apply to large-scale custom home projects.
Key Benefits 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, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a comfortable home of their own without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline 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 consuming open land, 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.
- 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 Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans based on your goals. Space is thoughtfully allocated to maximize function and livability.
- Permitting and City Approval — 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, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are fitted and completed to your specifications. A closing municipal review grants legal occupancy status and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few common profiles. If you are a homeowner with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors who already own residential properties are also well suited 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. Sites with underground infrastructure conflicts may require additional review. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take several months in San Jose, so planning ahead matters. Smaller detached units may complete more quickly, while larger new construction ADUs here require more time.
What does ADU construction cost in San Jose?
Budget requirements differ based on whether it's a conversion or new construction. In the San Jose area, 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. A detailed estimate can only be developed after a full site assessment.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to vacate the property during ADU construction?
Generally speaking, you do not need to vacate your house during ADU construction. Most job sites are structured to allow you continue living in the home throughout the construction timeline. Exceptions may arise if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our project managers will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as the main residence — typically 50 years or more. How long it lasts comes down to the standard of construction, whether the unit is properly cared for, and how proactively issues are resolved over time. We select commercial-grade materials and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. Proximity to transit corridors can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Planning Session Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. The process begins with a thorough and honest property review where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to schedule a site visit. No matter where you are in the decision-making process, we enjoy discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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