Expand Your Home with Professional ADU Construction
Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with craftsmanship and transparency.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to build 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 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 project. Our team understands the local permitting process, the engineering considerations, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could look like on 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 entryway — 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 below-grade dwelling units.
Mechanically, the process begins with a comprehensive review of your lot, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. 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 level of craftsmanship at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a private, independent living space without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Streamlined Approval Process — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of requiring new development, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both functional space and financial upside.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, the build starts. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. This phase, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A closing municipal review grants legal occupancy status and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you own a single-family home with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Property investors and rental owners who want to maximize their land are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property case by case to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction typically ranges from six to fourteen months, based on the project scope and city review schedules. 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 can move faster, while custom detached builds require more time.
What does ADU construction typically cost?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be produced following a full site assessment.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on where the ADU is read more being built. Standalone ADU projects are typically less disruptive, 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. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the build. There are edge cases if major utility upgrades affect the main house in ways that temporarily impact livability. Our construction supervisors will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials should last as long as your primary home — indefinitely with proper upkeep. Durability depends to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our team's knowledge of this region's building landscape means smoother project delivery from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. We bring licensed expertise in ADU construction across a wide range of project types — from small attached additions to fully independent secondary homes. Every project starts with a comprehensive site assessment where we understand your vision and share clear expectations of what the project will involve.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, 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