Transform Your Property with Professional ADU Construction
Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners see these visions here to life with craftsmanship and transparency.
The interest in ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. 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 apply deep hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could do for your property, this guide will walk you through 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 fully independent living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, 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 builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction offers family members a comfortable home of their own without losing proximity to the family.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to your specific needs.
- Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- 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 team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to maximize function and livability.
- Permitting and City Approval — 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, responding to review feedback promptly.
- Site Preparation and Foundation Work — 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 roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A final city inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already in a good starting place. 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 needs a dedicated professional workspace and wants a detached creative or business space that is distinct from your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may need a modified approach. Our team can assess each property on its own merits to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. Permitting alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions often finish in the lower end of the range, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a thorough property review.
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. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the build. Exceptions may arise if significant structural connections require temporary shutoffs 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 hold up?
A well-built ADU is designed to last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to large custom detached cottages. The process begins with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Get in touch with our office to schedule a site visit. Whether you're in the early stages of planning, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. 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