Transform Your Property with Professional ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest 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 supported hundreds of local homeowners bring these projects to life with precision and transparency.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to construct 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 job. Our team understands the local permitting process, the engineering details, and the design choices that make an ADU truly livable. Should you want to learn about 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 — including a kitchen, bathroom, sleeping area, and its own access point — that exists on the same lot as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins with a detailed site assessment, 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 permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate 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 align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we use on major custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction contributes significant 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.
- Multi-Generational Living — ADU construction provides adult children a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has cut down the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, the build starts. This covers land preparation, completing foundation work, and setting up utilities.
- Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A final city inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who runs a small business and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a full site assessment.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may create short-term inconveniences 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?
For the majority of homeowners, you do not need to vacate your house during ADU get more info construction. The vast majority of projects are designed so that you stay in your primary unit throughout the build. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the kickoff meeting.
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 — typically 50 years or more. Durability depends to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. We select commercial-grade materials and build to current California residential standards to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from the first meeting to the final inspection.
Start Your ADU Construction Consultation Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction for many different project types — from small attached additions to multi-room backyard residences. The process begins with a comprehensive site assessment where we understand your vision and provide an honest assessment of what the project will involve.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we enjoy 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632