Expand Your Home with Quality ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with precision and transparency.
The popularity of ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has simplified the process 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 functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the design choices that make an ADU beautiful. Should you want to learn about what ADU construction could do for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction describes the process of engineering, filing for, and completing 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 entrance — 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, everything kicks off with a thorough property evaluation, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. 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 completely finished living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same technical discipline we bring to full custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable 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 comfortable home of their own without leaving the property.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has reduced 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 works within your current footprint 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 residents have their own space.
- Lasting Financial Benefit — A well-built ADU remains an asset for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — 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 time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create precise architectural drawings tailored to your needs. Every square foot is planned to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for review and approval. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and establishing utility connections.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. A final city inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few recognizable groups. If you are a homeowner with a backyard, garage, or basement that could be converted, 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 supporting elderly parents.
Another strong candidate is someone who runs a small business 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 long-term value is proven.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. read more Parcels in historic districts or HOA-restricted communities may need a modified approach. Our experts will evaluate each property on its own merits to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction generally 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 city review schedules. Permitting alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions 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. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Projects that connect to the main structure may require temporary access 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?
In most cases, you are not required to vacate your main home during ADU construction. Most job sites are designed so that you remain on the property throughout the process. Exceptions may arise if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will walk you through any potential disruptions during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight should last as long as your primary home — indefinitely with proper upkeep. How long it lasts comes down to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels 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. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from the first meeting to the final inspection.
Start 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 across a wide range of project types — from modest studio builds to multi-room backyard residences. Our approach opens with a thorough and honest property review where we understand your vision and provide an honest assessment of what ADU construction on your property will look like.
Reach out to our team to set up your consultation. 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. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632