Expand Your Home with Quality ADU Construction
Homeowners across 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 powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and integrity.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. 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 build. Our team understands the local permitting process, the engineering considerations, and the aesthetic decisions that make an ADU truly livable. When you're ready to explore what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is an ADU Build?
ADU construction involves 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 — including a kitchen, bathroom, sleeping area, and its own entryway — 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, the process begins with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which includes foundation 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 separates excellent ADU construction from an average project 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 high standards we bring to full custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a self-contained residence without losing proximity to the family.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, 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 continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what's possible before any resources go toward planning.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints reflecting your priorities. Every square foot is planned to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A closing municipal review confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who want to maximize their land 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 require additional review. Brother & Brother Builders reviews each property individually and honestly to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions often finish in the lower end of the range, while custom detached builds require more time.
What does ADU construction cost in San Jose?
Costs vary widely based on the type and size of the ADU. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be produced following a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on the project's location on your property. New construction in the rear yard are usually easier to live alongside, since work happens away from the main house. Interior conversions may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your house during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the process. Exceptions may arise if interior conversion work touches shared systems in ways that briefly affect habitability. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies commercial-grade materials and comply with all local building codes to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has likely worked nearby.
Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's click here knowledge of these local conditions means smoother project delivery from design through the final walkthrough.
Schedule 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. Our builders provide licensed expertise in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. The process begins with a detailed, no-pressure consultation where we learn what you're trying to accomplish and give you a realistic picture of what the project will involve.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632