Transform Your Property with Expert ADU Construction
Property owners throughout 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 create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with precision and integrity.
The interest in 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 address housing needs. Whether you're building 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 knows the San Jose building codes, 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 an ADU Build?
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 self-contained living space — equipped with 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 basement or interior conversions.
Mechanically, the work starts 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 relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. 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 adds measurable 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 gives aging parents a private, independent living space without losing proximity to the family.
- Customization Options — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of expanding urban sprawl, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any time is invested in drawings.
- Blueprint Development and Layout Design — Licensed architects and designers create precise architectural drawings based on your goals. Layouts are carefully considered to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This covers land preparation, completing foundation work, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the agreed design. A closing municipal review confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families supporting elderly parents.
You may also be someone who needs a dedicated professional workspace and wants a private work environment that doesn't interfere with your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may need a modified approach. Brother & Brother Builders reviews each property case by case to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take a significant portion of the overall timeline in San Jose, so starting early is important. Simpler garage conversions often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely based on whether it's a conversion or new construction. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be given after completing a full site assessment.
Is ADU construction disruptive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the build. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. 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 is designed to last as long as your primary home — often several decades with routine maintenance. Longevity is tied to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. Brother & Brother Builders specifies residential-grade products rated for longevity 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 diverse mix 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. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes read more more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
San Jose's permitting office follows defined procedures for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our familiarity with the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
When you want to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our builders provide licensed expertise in ADU construction including all types of project types — from modest studio builds to large custom detached cottages. Our approach opens with a detailed, no-pressure consultation where we understand your vision and give you a realistic picture of what's achievable.
Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, our team is happy to 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