Transform Your Property 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 creates a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with skill and integrity.
The popularity of ADU construction has surged in recent years, and it's not hard to see why. California state website law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. If you're planning 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 details, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could look like on your property, this guide covers 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 self-contained living space — equipped with a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Materials must be selected to align with the neighborhood's character. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction adds measurable 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 provides adult children a comfortable home of their own without losing proximity to the family.
- Customization Options — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU remains an asset 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 team visits your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This includes grading the site, completing foundation work, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A last official inspection issues the certificate of occupancy and the ADU is ready 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 a backyard, garage, or basement that could be converted, 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.
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. 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 sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may face additional constraints. Brother & Brother Builders reviews each property individually and honestly to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. City review on its own can take two to four months in San Jose, so planning ahead matters. Smaller detached units can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Interior conversion projects are generally priced lower, sometimes between $75,000 and $140,000. 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?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are generally the least intrusive, since the construction zone is separate. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you do not need to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you remain on the property throughout the process. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. 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 last?
Any ADU built to code with professional oversight should last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with these local conditions means fewer surprises from design through the final walkthrough.
Start Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide years of hands-on experience in ADU construction for many different project types — from small attached additions to fully independent secondary homes. Our approach opens 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.
Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, our team is happy to 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632