Expand Your Home with Quality ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with skill and integrity.
The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property works.
At Brother & Brother Builders, we draw on extensive 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 mean for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction describes 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 — equipped with a kitchen, bathroom, sleeping area, and its own entrance — that is located on the same parcel as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the work starts with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. 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 encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same technical discipline we use on major custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — 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.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of consuming open land, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.
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 step tells you exactly what can be built before any resources go toward planning.
- Blueprint Development and Layout Design — Our design team create comprehensive blueprints reflecting your priorities. Every square foot is planned to optimize daily use.
- Permitting and City Approval — 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, 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, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you own a single-family home 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 common 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 is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property case by case to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. City review on its own can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. 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 whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you won't have to vacate your primary residence during ADU construction. Most builds are designed so that you stay in your primary unit throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety 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. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means more accurate timelines website and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer years of hands-on experience in ADU construction for many different project types — from small attached additions to multi-room backyard residences. The process begins with a thorough and honest property review where we learn what you're trying to accomplish and give you a realistic picture of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. 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. Building an ADU is a major decision — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632