Expand Your Home with Expert ADU Construction
Homeowners across San Jose, CA are realizing 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 generate rental income. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with craftsmanship and care.
The popularity of 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 build these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. Whether you're building 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 bring years of hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about 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 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 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, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, 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.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Materials must be selected to align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders get more info handles every ADU construction job 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 generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Customization Options — From open-plan one-bedrooms, ADU construction is adaptable to your specific needs.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which supports broader sustainability goals.
- Independent Living Areas — 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 continues to produce returns for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any money is spent on design.
- Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings reflecting your priorities. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. At this stage, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A last official inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Good Candidate 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 available square footage under zoning rules, you're already well-positioned. Homeowners wanting to add a revenue stream 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 doesn't interfere with your family's daily life. Real estate-minded homeowners who are building a portfolio are also prime candidates for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property case by case to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. Permitting alone can take a significant portion of the overall timeline 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 custom detached builds take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors 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 standalone backyard unit. Garage conversions often come in under, sometimes between $75,000 and $140,000. An accurate budget 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 where the ADU is being built. Standalone ADU projects are typically less disruptive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during key milestones. 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. The vast majority of projects are designed so that you remain on the property throughout the build. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — typically 50 years or more. Durability depends to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Our builds use commercial-grade materials and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office has developed specific protocols for ADU construction that require a builder familiar with local expectations. 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 smoother project delivery from the first meeting to the final inspection.
Book Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. We bring licensed expertise in ADU construction for many different project types — from small attached additions to fully independent secondary homes. The process begins with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture of what's achievable.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and help you take the next step. ADU construction is a significant investment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632