Transform Your Property with Expert ADU Construction
Homeowners across San Jose, CA are finding 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 house a family member. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with precision and transparency.
The popularity of ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add 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 works.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, 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 covers everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to the process of designing, permitting, and building 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 entrance — that sits on the same property 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, everything kicks off with a comprehensive review of your lot, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the local building department. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Materials must be selected to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.
Key Reasons to Choose 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.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction offers family members a private, independent living space without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process 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.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by roofing, siding, windows, and exterior doors. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to your specifications. A last official inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few clear categories. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who runs a small business and wants a separate office website 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 the return on investment is well-documented.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may face additional constraints. Brother & Brother Builders reviews each property individually and honestly to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take several months in San Jose, so planning ahead matters. Simpler garage 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. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you do not need to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you stay in your primary unit throughout the process. Certain situations could require a brief departure 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 remain in good condition?
An ADU constructed with quality materials should 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 how proactively issues are resolved over time. Our builds use commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area 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 families expand. Whether your property is near downtown San Jose, our team has likely worked nearby.
The City of San Jose's building department follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.
Schedule Your ADU Construction Consultation Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide 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 learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to schedule a site visit. Even if you're just exploring the idea, our team is happy 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