Transform Your Property with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical 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 turn these plans to life with craftsmanship and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have encouraged 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 works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, 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 explains everything you need to know.
What Is an ADU Build?
ADU construction describes 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 entrance — that is located on the same parcel 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 thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected 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 use on major custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often increasing appraised value substantially 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.
- Space for Loved Ones — ADU construction offers family members a private, independent living space without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent 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 usable housing and equity growth.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Our design team create detailed floor plans reflecting your priorities. Layouts are carefully considered to maximize function and livability.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A last official inspection grants legal occupancy status and your new space is cleared 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 have a residential property with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who works from home and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who want to maximize their land are also prime candidates for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may require additional review. 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 typically 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. Smaller detached units may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction usually run in terms of budget?
Costs vary widely based on the type and size of the ADU. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be produced following a formal feasibility evaluation.
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 usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may involve some shared wall work during key milestones. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you won't have to vacate your main home during ADU construction. Most job sites are set up to let you continue living in the home throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. Our construction supervisors will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight should last as long as the main residence — often several decades with routine maintenance. Durability depends to the standard of construction, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies high-quality components and comply with all local building codes to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department applies particular standards for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our team's knowledge of the San Jose permitting environment means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer licensed expertise in ADU construction including all types of project types check here — from modest studio builds to fully independent secondary homes. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what's achievable.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects and help you take the next step. 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