Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with skill and transparency.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. 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 draw on extensive 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 mean for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including 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 interior space reconfigurations.
Mechanically, everything kicks off with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a self-contained residence without losing proximity to the family.
- Design Flexibility — From modern studio layouts, ADU construction is adaptable to your specific needs.
- Streamlined Approval Process — Recent state legislation has reduced the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints tailored to your needs. Space is thoughtfully allocated to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for review and approval. We manage this entire process on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople 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.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A final city inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few clear categories. If you are a homeowner 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 financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits 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 already own residential properties are also well suited for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our team can assess each property individually and honestly to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. City review on its own can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be produced following a thorough property review.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Projects that connect to the main structure may require temporary access during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
For the majority of homeowners, more info you are not required to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the construction timeline. 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 hold up?
Any ADU built to code with professional oversight can be expected to last as long as the main residence — often several decades with routine maintenance. Longevity is tied to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can impact the design approach for a given ADU project. Our familiarity with this region's building landscape means smoother project delivery from the first meeting to the final inspection.
Book Your ADU Construction Assessment Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction including all types of project types — from simple garage conversions to fully independent secondary homes. Our approach opens with a thorough and honest property review where we listen to your goals and provide an honest assessment of what the project will involve.
Reach out to our team to set up your consultation. No matter where you are in the decision-making process, we're glad to answer questions, share examples of our work and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632