Transform Your Property with Professional ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with precision and transparency.
The demand for ADU construction has surged in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to construct 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 provides increased 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 requirements, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including a kitchen, bathroom, sleeping area, and its own access point — 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 detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from 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 wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — 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 provides adult children a comfortable home of their own without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction may be customized to the intended occupant's lifestyle.
- Streamlined Approval Process — 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.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of expanding urban sprawl, which aligns with 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 remains an asset for decades, providing both usable housing and equity growth.
The ADU Construction Process 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 phase answers exactly what can be built before any time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create precise architectural drawings reflecting your priorities. 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 inspection and clearance. We manage this entire process on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are issued, the build starts. This covers land preparation, completing foundation work, and setting up utilities.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A final city inspection issues the certificate of occupancy and the unit is officially approved 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 are a homeowner with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven 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 remains away from your family's daily life. Landlords and real estate investors who already own residential properties are also prime candidates for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property case by case to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The complete duration 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 beginning the process sooner rather than later is wise. Smaller detached units can move faster, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A detailed estimate can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to vacate the property during ADU construction?
In most cases, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the construction timeline. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials can be expected to last as long as your primary home — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. We select high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their properties accommodate detached backyard units nicely. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park more info corridor to those near Branham Lane, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. Every project starts with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, 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