Brother & Brother Builders

Transform Your Property with Expert 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 provides a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and care.

The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to construct 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 gives you more control over how your property works.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering details, and the design choices that make an ADU truly livable. When you're ready to explore what ADU construction could mean 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 complete 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 includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.

Mechanically, everything kicks off with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the local building department. 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 attached to or separate from your main home.

The difference between a good and a great ADU build is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same technical discipline we use get more info on major custom home projects.

Key Benefits 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.
• Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
• Space for Loved Ones — ADU construction offers family members a private, independent living space without losing proximity to the family.
• Design Flexibility — From modern studio layouts, ADU construction is adaptable to your specific needs.
• Simplified Regulatory Path — Recent state legislation has reduced the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Responsible Property Development — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
• Lasting Financial Benefit — A well-built ADU holds its value for decades, providing both usable housing and equity growth.

The ADU Construction Procedure Step by Step

1. Site Evaluation and Zoning Analysis — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any time is invested in drawings.
2. Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Every square foot is planned to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose requires submitting plans 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.
4. Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and setting up utilities.
5. Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
6. MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A last official inspection confirms the unit is code-compliant and your new space is cleared 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 have a residential property with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.

You may also be someone who runs a small business and wants a separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.

Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Our experts will evaluate each property case by case to recommend the right path forward.

ADU Construction Frequently Asked Questions

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

The full timeline for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and city review schedules. Permitting alone can take several months in San Jose, so planning ahead matters. Smaller detached units may complete more quickly, while custom detached builds take longer to complete.

What does ADU construction typically cost?

Budget requirements differ based on whether it's a conversion or new construction. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a thorough property review.

Is ADU construction disruptive while it's underway?

The level of disruption depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. Garage conversions or attached additions may require temporary access during key milestones. Our team communicates clearly about upcoming work and timelines.

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. Most job sites are set up to let you remain on the property throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will walk you through any potential disruptions during the planning phase.

How long will an ADU built through professional ADU construction hold up?

A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. Durability depends to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds use residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.

ADU Construction for San Jose Homeowners

Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has likely worked nearby.

The City of San Jose's building department follows defined procedures 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. Brother & Brother Builders' experience across the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.

Book Your ADU Construction Planning Session Today

Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction across a wide range of project types — from modest studio builds to fully independent secondary homes. Every project starts with a thorough and honest property review where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.

Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, we enjoy walk through your options, review completed projects and give you the clarity you need to move forward. 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