Transform Your Property with Expert ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
The popularity of ADU construction has increased significantly 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 embraced 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 serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU truly livable. If you've been thinking 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 involves the process of designing, permitting, and building 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 sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage website conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction transitions to 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 sets quality ADU construction apart is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains 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.
- Housing for Extended Family — ADU construction gives aging parents a comfortable home of their own without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to your specific needs.
- Simplified Regulatory Path — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for decades, providing both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what can be built before any time is invested in drawings.
- Custom Design and Architectural Planning — Our design team create detailed floor plans reflecting your priorities. Layouts are carefully considered to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are issued, physical construction begins. This covers land preparation, laying the structural base, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to the agreed design. A closing municipal review grants legal occupancy status and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction often belong to a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already well-positioned. 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 private work environment that is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.
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 face additional constraints. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while multi-room detached cottages require more time.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction commonly costs $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. An accurate budget can only be developed after a thorough property review.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. 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 do not need to vacate your primary residence during ADU construction. Most builds are set up to let you continue living in the home throughout the process. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. Durability depends to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes 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 ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
Local regulatory bodies in this area applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with the San Jose permitting environment means more accurate timelines and budgets from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction for many different project types — from simple garage conversions to fully independent secondary homes. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and give you a realistic picture of what ADU construction on your property will look like.
Get in touch with our office to begin the conversation. 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. ADU construction is a significant investment — 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