Transform Your Property with Quality ADU Construction
Families in 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 create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
The demand for ADU construction has increased significantly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you're building 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 apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering considerations, and the planning steps that make an ADU functional. When you're ready to explore what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction refers to 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 — 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 interior space reconfigurations.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we use on major custom home projects.
Key Benefits 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.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without losing proximity to the family.
- Customization Options — From open-plan one-bedrooms, ADU construction may be customized to your specific needs.
- Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both usable housing and equity growth.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any resources go toward planning.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A closing municipal review confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you have a residential property with available square footage under zoning rules, you're already well-positioned. 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 separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners 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 lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may face additional constraints. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take two to four months in San Jose, so starting early is important. Straightforward interior conversions often finish in the lower end of the range, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Interior conversions may require temporary access during key milestones. We provide advance notice about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials can be expected to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and build to current California residential standards to protect your investment for the long haul.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. 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 the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.
Start Your ADU Construction Consultation Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU click here construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we listen to your goals and share clear expectations of what's achievable.
Get in touch with our office to begin the conversation. Even if you're just exploring the idea, we enjoy answer questions, share examples of our work and help you take the next step. ADU construction is a significant investment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632