Unlock New Space with Professional ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and transparency.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. If you're planning 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 bring years of hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering details, 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 covers everything you need to know.
What Is an ADU Build?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained 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 detailed site assessment, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. 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 depth of planning at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real 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.
- Space for Loved Ones — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what ADU types will work before any resources go toward planning.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints reflecting your priorities. 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. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This covers land preparation, pouring the concrete foundation, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, 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 runs a small business and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also prime candidates for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to website pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property on its own merits to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. City review on its own can take several 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 larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing a thorough property review.
Is ADU construction disruptive while it's underway?
The level of disruption depends on the project's location on your property. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work 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?
In most cases, you do not need to vacate your main home during ADU construction. Most builds are designed so that you continue living in the home throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our construction supervisors will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU should last as long as your primary home — often several decades with routine maintenance. How long it lasts comes down to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area have found their lots work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as families expand. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
San Jose's permitting office follows defined procedures for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our team's knowledge of these local conditions means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. The process begins with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and make sure you feel confident before committing. 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