Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
The popularity of ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have embraced 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 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 considerations, and the planning steps that make an ADU functional. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes 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 entrance — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even adu construction near San Jose basement or interior conversions.
Mechanically, the process begins with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same professional rigor we bring to full custom home projects.
Key Advantages 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, generating steady monthly revenue for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a self-contained residence without moving to another neighborhood.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process 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 aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU remains an asset for decades, providing both usable housing and equity growth.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what can be built before any time is invested in drawings.
- Custom Design and Architectural Planning — Licensed architects and designers create comprehensive blueprints reflecting your priorities. Layouts are carefully considered 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 review and approval. We manage this entire process on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are granted, on-site work kicks off. This includes grading the site, laying the structural base, and establishing utility connections.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Every system is reviewed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected 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?
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 in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
You may also be someone who runs a small business and wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Brother & Brother Builders reviews each property individually and honestly to advise you on what's feasible.
ADU Construction FAQ
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. Permitting alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
The day-to-day impact 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 require temporary access during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
In most cases, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow you continue living in the home throughout the process. There are edge cases if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will walk you through any potential disruptions 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 can be expected to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. We select residential-grade products rated for longevity and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Consultation Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction across a wide range of project types — from simple garage conversions to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture of what the project will involve.
Get in touch with our office to begin the conversation. 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632