Transform Your Property with Professional ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding 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 supported hundreds of local homeowners bring these projects to life with craftsmanship and integrity.
The demand for ADU construction has surged in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have embraced 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 gives you more 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 design choices that make an ADU functional. When you're ready to explore what ADU construction could mean for your property, this guide covers everything you need to know.
What Is ADU Construction?
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 — featuring a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the work starts with a comprehensive review of your lot, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, 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. Products need to be chosen 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 technical discipline we use on major custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often returning more than the build cost 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 self-contained residence without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has reduced 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 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 produces a fully self-contained unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Licensed architects and designers create precise architectural drawings based on your goals. Layouts are carefully considered to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. We manage this entire process on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This covers land preparation, laying the structural base, and establishing utility connections.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A last official inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few common profiles. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. 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 Common Questions Answered
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. Permitting alone can take a significant portion of the overall timeline in San Jose, so starting early is important. Simpler garage conversions can move faster, while larger new construction ADUs 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 whether it's a conversion or new construction. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be developed after a formal feasibility evaluation.
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 generally the least intrusive, since the construction zone is separate. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your primary residence during ADU construction. Most builds are designed so that you continue living in the home throughout the build. There are edge cases if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as your primary home — indefinitely with proper upkeep. How long it lasts comes down to the systems installed, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as housing demand rises. From neighborhoods here near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
San Jose's permitting office has developed specific protocols 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. Brother & Brother Builders' experience across these local conditions means smoother project delivery from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. The process begins with a thorough and honest property review where we understand your vision and share clear expectations of what the project will involve.
Reach out to our team to set up your consultation. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and help you take the next step. 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