Expand Your Home with Quality ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with craftsmanship and integrity.
The interest in ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct 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 provides increased control over how your property functions.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU functional. Should you want to learn about what ADU construction could look like on your property, this guide will walk you through 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 — including a kitchen, bathroom, sleeping area, and its own access point — 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 interior space reconfigurations.
Mechanically, the work starts with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Products need to be chosen to complement the existing structure. 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
- Boosted Home Equity — 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 can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — 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 the long haul by offering both usable housing and equity growth.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any money is spent on design.
- Architectural Drafting and Space Planning — Our design team create precise architectural drawings reflecting your priorities. Layouts are carefully considered to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, physical construction begins. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already a strong candidate. 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 works from home and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our team can assess each property case by case to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. City review on its own can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions often finish in the lower end of the range, while multi-room detached cottages require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on the project's location on your property. Standalone ADU projects are usually easier to live alongside, since the construction zone is separate. Garage conversions or attached additions may create short-term inconveniences during key milestones. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
In most cases, you won't have to vacate your primary residence during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that temporarily impact livability. The team at Brother & Brother Builders will walk you through any potential disruptions during the planning phase.
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 any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Our builds use commercial-grade materials and comply with all local building codes 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 well suited for ADU construction. Homeowners in the Willow Glen neighborhood 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 knows the permitting landscape well.
The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. 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 kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
If you're ready to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer licensed expertise in ADU construction for many different project types — from small attached additions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we understand your vision and share clear expectations of what ADU construction on your property will look like.
Get in touch with our office to more info schedule a site visit. Whether you're in the early stages of planning, we're glad to walk through your options, review completed projects and help you take the next step. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632