Brother & Brother Builders

Expand Your Home with Quality ADU Construction

Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with precision and care.

The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. 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 serves your household.

At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could look like on your property, this guide will walk you through 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 self-contained living space — equipped with 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 professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit adjacent to or detached from your main home.

The difference between a good and a great ADU build is the depth of planning at every stage. Components should be specified to align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we bring to full custom home projects.

Key Reasons to Choose ADU Construction

• Higher Resale Potential — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
• Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
• Multi-Generational Living — ADU construction provides adult children a comfortable home of their own without moving to another neighborhood.
• Personalized Layouts — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
• Simplified Regulatory Path — Recent state legislation has minimized the barriers and delays associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
• Responsible Property Development — Building an ADU uses your existing lot instead of consuming open land, which contributes to sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
• Long-Term Investment Security — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.

The ADU Construction Procedure Step by Step

1. Initial Property Assessment and Feasibility Review — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any resources go toward planning.
2. Custom Design and Architectural Planning — Licensed architects and designers create precise architectural drawings reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
3. Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. We manage this entire process on your behalf, addressing any city comments promptly.
4. Ground Prep and Structural Base — Once permits are approved, the build starts. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
5. Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. At this stage, the ADU takes its visible shape.
6. MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. All work is inspected at designated stages throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A closing municipal review issues the certificate of occupancy and the ADU is ready for use.

Who Is a Good Candidate for ADU Construction?

Property owners who are best suited from ADU construction typically fall into a few common profiles. If you own a single-family home with available square footage under zoning rules, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.

ADU construction also suits someone who works from home and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who already own residential properties are also a natural fit for ADU construction, since the long-term value is proven.

Those who should discuss alternatives first include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property on its own merits to provide realistic options.

ADU Construction Frequently Asked Questions

How long does ADU construction usually 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. City review on its own can take several months in San Jose, so planning ahead matters. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.

What does ADU construction cost in San Jose?

Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing 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 being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Projects that connect to the main structure may require temporary click here access during certain phases of construction. Our team communicates clearly about what to expect at each stage.

Do I need to move out during ADU construction?

In most cases, you are not required to vacate your house during ADU construction. Most job sites are structured to allow you continue living in the home throughout the build. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. Our construction supervisors will flag these situations 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 the main residence — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. We select 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

The communities throughout San Jose provide a diverse mix of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.

San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means more accurate timelines and budgets from the first meeting to the final inspection.

Start Your ADU Construction Consultation Today

When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. Every project starts with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what's achievable.

Contact Brother & Brother Builders to schedule a site visit. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and help you take the next step. ADU construction is a significant investment — and we're committed to helping you get it right.

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