Transform Your Property with Expert ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with precision and integrity.
The popularity of ADU construction has increased significantly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering considerations, and the planning steps that make an ADU beautiful. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring 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 interior space reconfigurations.
Mechanically, the work starts with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction enters the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — 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 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 comfortable home of their own without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess 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.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints tailored to your needs. 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. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to the approved plan. A final city inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who runs a small business and wants a detached creative or business space that doesn't interfere with your family's daily life. Real estate-minded homeowners who want to maximize their land are also prime candidates for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts 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 usually take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while custom detached builds take longer to complete.
What does ADU construction typically cost?
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 standalone backyard unit. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to move out during ADU construction?
In most cases, you won't have to vacate your primary residence during ADU construction. Most builds are structured to allow you continue living in the home throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. Our project managers will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. Whether your property is near downtown San Jose, our team has likely worked nearby.
San Jose's permitting office has developed specific protocols for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with these local conditions means smoother project delivery from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. The process begins with a thorough and honest property review where we listen to your goals and share clear expectations of what the project will involve.
Contact Brother & Brother Builders to set more info up your consultation. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects and give you the clarity you need to move forward. 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