Transform Your Property with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding 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 helped hundreds of local homeowners see these visions to life with precision and integrity.
The demand for ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you want to build 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 apply deep hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the design choices that make an ADU functional. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction involves 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 — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property 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, the process begins with a comprehensive review of your lot, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same high standards we bring to full custom home projects.
Key Reasons to Choose 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.
- Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of requiring new development, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU holds its value for decades, providing both functional space and financial upside.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans based on your goals. Space is thoughtfully allocated to maximize function and livability.
- Permit Submission and Municipal Review — 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, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are granted, the build starts. This covers land preparation, completing foundation work, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the approved plan. A final city 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 generally fit within a few common profiles. If you own a single-family home with available square footage under zoning rules, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who needs a dedicated professional workspace and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also prime candidates for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. City review on its own can take two to four months in San Jose, so starting early is important. Straightforward interior conversions may complete more quickly, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are generally the least intrusive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you continue living in the home throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight should last as long as any standard residential structure — often several click here decades with routine maintenance. Longevity is tied to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes to ensure lasting performance.
ADU Construction for Local 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 have seen growing ADU activity as families expand. Whether your property is near downtown San Jose, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our familiarity with these local conditions means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we understand your vision and give you a realistic picture of what the project will involve.
Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632