Transform Your Property with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with skill and care.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. 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. 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 functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering requirements, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could do for your property, this guide will walk you through 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 — including a kitchen, bathroom, sleeping area, and its own entryway — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins with a comprehensive review of your lot, 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 the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Products need to be chosen to align with the neighborhood's character. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Housing for Extended Family — ADU construction provides adult children a private, independent living space without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — 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.
- Durable Return on Investment — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what can be built before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are approved, physical construction begins. This covers land preparation, completing foundation work, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, 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 required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are placed and inspected to your specifications. A closing municipal review grants legal occupancy status and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you own a single-family home with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take several months in San Jose, so planning ahead matters. Straightforward interior conversions often finish in the lower end of the range, while custom detached builds require more time.
What does ADU construction typically cost?
Budget requirements differ based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on the project's location on your property. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may require temporary access during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps more info you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
For the majority of homeowners, you do not need to vacate your main home during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the build. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU is designed to last as long as your primary home — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and follow all code requirements 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 well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
The City of San Jose's building department 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 familiarity with these local conditions means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
When you want to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our builders provide proven skills in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. The process begins with a detailed, no-pressure consultation where we listen to your goals and share clear expectations of what the project will involve.
Get in touch with our office to schedule a site visit. Whether you're in the early stages of planning, our team is happy 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632