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 provides 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 turn these plans to life with skill and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to construct 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 provides increased control over how your property functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. When you're ready to explore what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of planning, approving, and constructing 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 entrance — that exists on the same lot as a primary residence. ADU construction can take several forms, 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 team evaluate setbacks, get more info zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. 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 Advantages 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.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Housing for Extended Family — ADU construction offers family members a private, independent living space without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which supports broader sustainability goals.
- Independent Living Areas — 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 holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Our design team create comprehensive blueprints reflecting your priorities. Layouts are carefully considered to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, pouring the concrete foundation, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. 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 operationally complete. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to the agreed design. A final city inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few recognizable groups. If you have a residential property with available square footage under zoning rules, 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 supporting elderly parents.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also a natural fit for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while custom detached builds take longer to complete.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Attached ADU additions often come in under, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a full site assessment.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may require temporary access during key milestones. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
In most cases, you are not required to vacate your house during ADU construction. Most job sites are structured to allow you remain on the property throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. 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 can be expected to last as long as your primary home — typically 50 years or more. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range 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. Neighborhoods near Blossom Hill Road have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across these local conditions means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction across a wide range of project types — from simple garage conversions to fully independent secondary homes. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture of what's achievable.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, our team is happy to 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 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