Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with skill and integrity.
The popularity of ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. If you're planning 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 build. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could do for 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 designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.
Key Reasons to Choose 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.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction offers family members a comfortable home of their own without moving to another neighborhood.
- Customization Options — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any time is invested in drawings.
- Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings tailored to your needs. Every square foot is planned to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings 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 includes grading the site, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Licensed subcontractors 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 fitted and completed to your specifications. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit 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 enough lot space to meet setback requirements, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone 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 check here often finish in the lower end of the range, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. The vast majority of projects are structured to allow you stay in your primary unit throughout the process. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies residential-grade products rated for longevity and comply with all local building codes 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 frequently see their parcels accommodate detached backyard units nicely. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
Local regulatory bodies in this area applies particular standards 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 familiarity with this region's building landscape means smoother project delivery from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer licensed expertise in ADU construction including all types of project types — from modest studio builds to fully independent secondary homes. Every project starts with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what the project will involve.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, our team is happy to walk through your options, review completed projects and make sure you feel confident before committing. ADU construction is a significant investment — 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