Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with skill and transparency.
The demand for 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 add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property works.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide will walk you through everything you need to know.
What Is the ADU Construction Process?
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 complete 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 below-grade dwelling units.
Mechanically, everything kicks off with a detailed site assessment, where our builders 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 moves into the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — 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 can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of requiring new development, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints tailored to your needs. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This involves leveling and prepping the ground, pouring the concrete foundation, and establishing utility connections.
- Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. At this stage, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Inspections are completed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting 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?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you are a homeowner with available square footage under zoning rules, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Brother & Brother Builders reviews each property case by case to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and city review schedules. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions often come in under, sometimes between $75,000 and $140,000. A precise cost projection can only be developed after a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on the project's location on your property. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may require temporary access 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. Most builds are set up to let you remain on the property throughout the process. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials can be expected to last as long as your primary home — often several click here decades with routine maintenance. Durability depends to the systems installed, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are well suited for ADU construction. Residents in the Rose Garden district have found their lots are well configured for ADU builds. The Berryessa area are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
Local regulatory bodies in this area applies particular standards for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our familiarity with the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we understand your vision and share clear expectations of what's achievable.
Contact Brother & Brother Builders to begin the conversation. Even if you're just exploring the idea, we're glad to answer questions, share examples of our work and make sure you feel confident before committing. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632