Unlock New Space with Quality ADU Construction

Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical 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 bring these projects to life with skill and integrity.

The popularity of ADU construction has surged in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have embraced 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 knows the San Jose building codes, the engineering considerations, and the planning steps that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.

What Is an ADU Build?

ADU construction describes the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own access point — 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 below-grade dwelling units.

Mechanically, the work starts with a thorough property evaluation, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans 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 completely finished living unit adjacent to or detached from your main home.

The difference between a good and a great ADU build is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same technical discipline we bring to full custom home projects.

Key Advantages ADU Construction

• Boosted Home Equity — ADU construction adds measurable 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.
• Space for Loved Ones — ADU construction offers family members a private, independent living space without leaving the property.
• Design Flexibility — From modern studio layouts, ADU construction may be customized to your specific needs.
• Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
• Responsible Property Development — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
• Separate Entrances and Spaces — 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 the long haul by offering both livable square footage and monetary benefit.

The ADU Construction Procedure Step by Step

1. Property Walkthrough and Feasibility Check — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what's possible before any resources go toward planning.
2. Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
4. Site Preparation and Foundation Work — Once permits are issued, the build starts. This covers land preparation, pouring the concrete foundation, and establishing utility connections.
5. Structural Framing and Weatherproofing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. At this stage, the ADU takes its visible shape.
6. MEP Systems Rough-In — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
7. Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.

Who Is a Right Fit for ADU Construction?

People who see the greatest return from ADU construction generally fit within a few common profiles. If you have a residential property 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 common ADU construction clients, along with families navigating multigenerational living situations.

You may also be someone who runs a small business and wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who are building a portfolio are also prime candidates 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 need a modified approach. Brother & Brother Builders reviews each property on its own merits to recommend the right path forward.

ADU Construction FAQ

How long does ADU construction typically take from start to finish?

The complete duration for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. The approval phase alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions often finish in the lower end of the range, while larger new construction ADUs require more time.

What does ADU construction usually run in terms of budget?

Budget requirements differ based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Attached ADU additions often come in under, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a full site assessment.

Is ADU construction intrusive while it's underway?

How much the build affects daily life depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Interior conversions may require temporary access during key milestones. Brother & Brother Builders keeps you informed about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

For the majority of homeowners, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow 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 project managers will walk you through any potential disruptions during the kickoff meeting.

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 the main residence — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes to deliver a structure that stands the test of time.

ADU Construction for Local Homeowners

Residential areas across San Jose present a wide range of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their click here properties are well configured for ADU builds. 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 has project experience in the area.

Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from design through the final walkthrough.

Book 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 ready to guide you. We bring licensed expertise in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment 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 make sure you feel confident before committing. Building an ADU is a major decision — and our goal is to ensure it delivers real value.

Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632