Expand Your Home with Quality ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest 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 see these visions to life with precision and integrity.
The demand for ADU construction has surged 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 understands the local permitting process, the engineering requirements, and the aesthetic decisions that make an ADU functional. Should you want to learn about what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property 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 process begins with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Products need to be chosen to align with the neighborhood's character. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — 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 may be listed 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 self-contained residence without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints based on your goals. Space is thoughtfully allocated to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are issued, physical construction begins. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. At this stage, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A last official inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few recognizable groups. If you own a single-family home with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners wanting to add a revenue get more info stream through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who are building a portfolio are also well suited for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may require additional review. Our experts will evaluate each property individually and honestly to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction typically 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 local permitting timelines. City review on its own can take two to four months in San Jose, so starting early is important. Simpler garage conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely based on the type and size of the ADU. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. A detailed estimate can only be developed after a full site assessment.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during certain phases of construction. 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 do not need to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the construction timeline. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight should last as long as any standard residential structure — often several decades with routine maintenance. Longevity is tied to the standard of construction, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a wide range of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots are well configured for ADU builds. The Berryessa area have seen growing ADU activity as families expand. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our team's knowledge of these local conditions means smoother project delivery from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is the team to call. Our experts offer licensed expertise in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. Every project starts 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. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and help you take the next step. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632