Expand Your Home with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with craftsmanship and transparency.
The interest in ADU construction has increased significantly in recent years, and it's not hard to see why. 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 increase density responsibly. 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 job. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU functional. Should you want to learn about what ADU construction could do for your property, this guide explains 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 complete living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that sits on the same property as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins with a comprehensive review of your lot, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit connected to or independent of your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same professional rigor we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — 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 can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a comfortable home of their own without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has reduced the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot 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 residents have their own space.
- Lasting Financial Benefit — A well-built ADU remains an asset 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 team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what can be built before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints based on your goals. Every square foot is planned to maximize function and livability.
- Filing for Building Permits — 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.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A final city inspection confirms the unit is code-compliant 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 generally fit within a few clear categories. If you have a residential property 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 common ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who needs a dedicated professional workspace 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 rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to advise you more info on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions may complete more quickly, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ 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. Attached ADU additions are generally priced lower, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your house during ADU construction. Most builds are designed so that you stay in your primary unit throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our project managers will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the systems installed, how well routine maintenance is performed, and if mechanical components are maintained on schedule. We select residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
San Jose's permitting office has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our team's knowledge of the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.
Start 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 experts offer years of hands-on experience in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. The process begins with a comprehensive site assessment where we understand your vision and provide an honest assessment of what ADU construction on your property will look like.
Reach out to our team to set up your consultation. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects 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