Unlock New Space with Professional ADU Construction
Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
The popularity of ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could look like on your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction refers to the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the work starts with a comprehensive review of your lot, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit adjacent to or detached 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 sized for independent daily use. Brother & Brother Builders treats each project with the same technical discipline we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your specific needs.
- Streamlined Approval Process — Recent state legislation has reduced the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU continues to produce returns for decades, providing both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what can be built before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered 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. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, the build starts. This includes grading the site, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Inspections are completed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to your specifications. A final city inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into 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 wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families supporting elderly parents.
You may also be someone who runs a small business and wants a private work environment that remains away from your family's daily life. Landlords and real estate investors who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include Brother & Brother Builders adu construction lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may face additional constraints. Brother & Brother Builders reviews each property case by case to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally 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 city review schedules. City review on its own can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your primary residence during ADU construction. Most builds are structured to allow you remain on the property throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
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 — indefinitely with proper upkeep. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Our builds use commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a diverse mix of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district frequently see their parcels accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has project experience in the area.
The City of San Jose's building department follows defined procedures for ADU construction that our team navigates routinely. 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 smoother project delivery from the first meeting to the final inspection.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is the team to call. Our experts offer licensed expertise in ADU construction for many different project types — from small attached additions to multi-room backyard residences. The process begins with a thorough and honest property review where we understand your vision 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 enjoy answer questions, share examples of our work and make sure you feel confident before committing. 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