Transform Your Property with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with skill and transparency.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged 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 apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU truly livable. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own access point — 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 builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Materials must be selected to complement the existing structure. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we bring to full custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a self-contained residence without moving to another neighborhood.
- Design Flexibility — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any time is invested in drawings.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, the build starts. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A closing municipal review grants legal occupancy status and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within 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 supporting elderly parents.
ADU construction also suits someone who needs a dedicated professional workspace and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who want to maximize their land 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 lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Our team can assess each property on its own merits to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take a significant portion of the overall timeline in San Jose, so starting early is important. 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 whether it's a conversion or new construction. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
How much the website build affects daily life depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Garage conversions or attached additions may require temporary access during certain phases of construction. We provide advance notice about what to expect at each stage.
Do I need to move out during ADU construction?
For the majority of homeowners, you do not need to vacate your house during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
A well-built ADU is designed to last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select commercial-grade materials and comply with all local building codes 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. Property owners near the Almaden Valley area often discover their properties work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means smoother project delivery 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 experts offer proven skills in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we listen to your goals and share clear expectations of what ADU construction on your property will look like.
Contact Brother & Brother Builders to schedule a site visit. No matter where you are in the decision-making process, we're glad to walk through your options, review completed projects and help you take the next step. This type of project is a meaningful commitment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632