Transform Your Property with Quality ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with skill and integrity.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. Whether you're building 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 project. Our team knows the San Jose building codes, the engineering requirements, and the design choices that make an ADU beautiful. If you've been thinking about what ADU construction could look like on your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction involves 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 — equipped with a kitchen, bathroom, sleeping area, and its own access point — 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 below-grade dwelling units.
Mechanically, everything kicks off with a comprehensive review of your lot, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced the barriers and delays associated with ADU construction, making the process that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU remains an asset for the long haul by offering both functional space and financial upside.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any resources go toward planning.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints tailored to your needs. Space is thoughtfully allocated to maximize function and livability.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. We manage this entire process on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review grants legal occupancy status and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few common profiles. If you own a single-family home with available square footage under zoning rules, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who runs a small business and wants a private work environment that is distinct from your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may face additional constraints. Brother & Brother Builders reviews each property on its own merits to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take several months in San Jose, so starting early is important. Straightforward interior conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. An accurate budget can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about what to expect at each stage.
Do I need to leave my home during ADU construction?
In most cases, you do not need to vacate your house during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the process. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight can be expected to last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area more info have found their lots work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. If you're located closer to Evergreen, our team knows the permitting landscape well.
The City of San Jose's building department has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Start Your ADU Construction Consultation Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we enjoy answer questions, share examples of our work and help you take the next step. 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