Expand Your Home with Professional ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with precision and transparency.
The popularity of ADU construction has surged in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property functions.
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 requirements, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete 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 can take several forms, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a comprehensive review of your lot, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a comfortable home of their own without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, resulting in a timeline 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.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for many years and generates both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create precise architectural drawings reflecting your priorities. Every square foot is planned to maximize function and livability.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are issued, physical construction begins. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to the agreed design. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into 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 needs a dedicated professional workspace and wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and city review schedules. City review on its own can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units 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?
Budget requirements differ based on the type and size of the ADU. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. A precise cost projection 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. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may require temporary access during certain phases of construction. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you won't have to vacate your primary residence during ADU construction. Most job sites are set up to let you get more info stay in your primary unit throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will walk you through any potential disruptions during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials is designed to last as long as your primary home — typically 50 years or more. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. 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
San Jose's neighborhoods offer a diverse mix of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as multigenerational living becomes more common. If you're located closer to Evergreen, our team knows the permitting landscape well.
Local regulatory bodies in this area applies particular standards for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Consultation Today
When you want 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 including all types of project types — from modest studio builds to multi-room backyard residences. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities 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