Unlock New Space with Professional ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with skill and care.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide will walk you through everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of engineering, filing for, and completing an accessory dwelling unit on get more info a residential property. An accessory dwelling unit is a fully independent living space — including 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 conversions, and even basement or interior conversions.
Mechanically, the work starts with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the local building department. 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 move-in-ready living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Components should be specified to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a private, independent living space without moving to another neighborhood.
- Customization Options — From two-bedroom configurations, ADU construction may be customized to your household's priorities.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of consuming open land, which contributes to 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 the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create detailed floor plans based on your goals. Every square foot is planned to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A last official inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you have a residential property with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners looking to generate income 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 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 well suited for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property case by case to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally 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. City review on its own can take several months in San Jose, so starting early is important. Smaller detached units can move faster, while custom detached builds take longer to complete.
What does ADU construction usually run in terms of budget?
Costs vary widely based on the type and size of the ADU. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences during certain phases of construction. Our team communicates clearly about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you are not required to vacate your house during ADU construction. The vast majority of projects are structured to allow you continue living in the home throughout the construction timeline. Exceptions may arise if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select high-quality components and build to current California residential standards to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction for many different project types — from modest studio builds to multi-room backyard residences. Every project starts with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture 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 give you the clarity you need to move forward. Building an ADU is a major decision — 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