Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are finding 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 house a family member. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and care.
The demand for ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to build 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 serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team understands the local permitting process, the website engineering details, and the design choices that make an ADU functional. If you've been thinking about what ADU construction could do for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — equipped with a kitchen, bathroom, sleeping area, and its own access point — 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 interior space reconfigurations.
Mechanically, the process begins with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same high standards we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Streamlined Approval Process — Recent state legislation has cut down the permitting obstacles associated with ADU construction, making the process that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU continues to produce returns for decades, providing both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners who already own residential properties 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 properties with significant setback limitations. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, based on the project scope and how quickly approvals come through. The approval phase alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions often come in under, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Projects that connect to the main structure may involve some shared wall work during key milestones. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
In most cases, you are not required to vacate your house during ADU construction. Most builds are designed so that you continue living in the home throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our project managers will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight should last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies residential-grade products rated for longevity and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties work well for both attached and detached projects. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
The City of San Jose's building department 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. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from design through the final walkthrough.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. We bring licensed expertise in ADU construction including all types of project types — from modest studio builds to multi-room backyard residences. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. No matter where you are in the decision-making process, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632