Transform Your Property with Professional 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 opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and transparency.
The popularity of ADU construction has surged 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 encouraged the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide will walk you through 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 fully independent living space — including a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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 builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we use on major custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction delivers real 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, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a private, independent living space without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — 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.
- Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, 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 operationally complete. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who works from home and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners who already own residential properties are also well suited 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. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our experts will evaluate each property case by case to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, based on the project scope and city review schedules. Permitting alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Costs vary widely based on the type and size of the ADU. In the San Jose area, website ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Projects that connect to the main structure may require temporary access during certain phases of construction. Our team communicates clearly about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you are not required to vacate your main home during ADU construction. Most job sites are structured to allow you remain on the property throughout the process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight can be expected to last as long as your primary home — indefinitely with proper upkeep. Durability depends to the standard of construction, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use commercial-grade materials and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. 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 require a builder familiar with local expectations. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means more accurate timelines and budgets from the first meeting to the final inspection.
Book Your ADU Construction Consultation Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our builders provide years of hands-on experience in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and share clear expectations of what the project will involve.
Get in touch with our office to begin the conversation. 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. 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