Transform Your Property with Professional ADU Construction
Property owners throughout 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 flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with precision and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. 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 address housing needs. 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 apply deep hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering considerations, and the planning steps that make an ADU functional. If you've been thinking about what ADU construction could mean for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the work starts with a thorough property evaluation, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the local building department. Once permits are secured, ADU construction transitions to the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the attention to detail 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 professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a self-contained residence without moving to another neighborhood.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, making the process that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of expanding urban sprawl, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU holds its value 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 builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, physical construction begins. This includes grading the site, completing foundation work, and establishing utility connections.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. This phase, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are fitted and completed to your specifications. A closing municipal review issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also prime candidates for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property individually and honestly to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in here this region, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a full site assessment.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. New construction in the rear yard are typically less disruptive, since the construction zone is separate. Interior conversions may create short-term inconveniences during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you are not required to vacate your house during ADU construction. Most builds are structured to allow you continue living in the home throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight can be expected to last as long as any standard residential structure — typically 50 years or more. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies 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 wide range of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means smoother project delivery from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and share clear expectations 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're glad to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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