Unlock New Space with Professional 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 creates a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and care.
The demand for ADU construction has increased significantly in recent years, and it's not hard to see 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. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
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 requirements, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could look like on 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 complete living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot 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 comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same technical discipline we use on major custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a self-contained residence without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your specific needs.
- Streamlined Approval Process — Recent state legislation has reduced the barriers and delays associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any resources go toward planning.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints based on your goals. Layouts are carefully considered to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Every system is reviewed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A last official inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction often belong to a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, 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.
ADU construction also suits someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Property investors and rental owners who already own residential properties are also a natural fit for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may face additional constraints. Brother & Brother Builders reviews each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units often finish in the lower end of the range, while custom detached builds take longer to complete.
What does ADU construction typically cost?
Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on the project's location on your property. Detached more info backyard builds are usually easier to live alongside, since work happens away from the main house. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
In most cases, you won't have to vacate your house during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the process. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will discuss these scenarios during the planning phase.
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 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. We select commercial-grade materials 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 well suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. 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 likely worked nearby.
Local regulatory bodies in this area follows defined procedures for ADU construction that experienced builders know well. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means smoother project delivery from design through the final walkthrough.
Book 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. We bring proven skills in ADU construction including all types of project types — from simple garage conversions to fully independent secondary homes. Every project starts with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to set up your consultation. Whether you're in the early stages of planning, we're glad to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632