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 most rewarding investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and care.

The demand for ADU construction has increased significantly 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 encouraged the trend as a way to expand the housing supply. If you're planning 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 draw on extensive hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering considerations, and the design choices that make an ADU truly livable. 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 ADU Construction?

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 fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entrance — 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 interior space reconfigurations.

Mechanically, everything kicks off with a thorough property evaluation, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit adjacent to or detached from your main home.

What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders treats each project with the same technical discipline we bring to full custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
• Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Housing for Extended Family — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
• Customization Options — From open-plan one-bedrooms, ADU construction can be tailored to your specific needs.
• Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
• Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
• Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both usable housing and equity growth.

The ADU Construction Process Step by Step

1. Property Walkthrough and Feasibility Check — 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 time is invested in drawings.
2. Custom Design and Architectural Planning — Our design team create comprehensive blueprints tailored to your needs. Layouts are carefully considered to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. We manage this entire process on your behalf, addressing any city comments promptly.
4. Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
6. MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
7. Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.

Who Is a Good Candidate for ADU Construction?

Property owners who are best suited 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 in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.

You may also be someone who runs a small business and wants a detached creative or business space that doesn't interfere with your family's daily life. Real estate-minded homeowners who already own residential properties 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 lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our experts will evaluate each property on its own merits to recommend the right path forward.

ADU Construction Frequently Asked Questions

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

The full timeline for ADU construction usually runs between 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 starting early is important. Simpler garage conversions often finish in the lower end of the range, while multi-room detached cottages require more time.

What does ADU construction usually run in terms of budget?

Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. A precise cost projection can only be given after completing a formal feasibility evaluation.

Is ADU construction intrusive while it's underway?

The level of disruption depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.

Do I need to leave my home during ADU construction?

Generally speaking, you are not required to vacate your primary residence during ADU construction. Most builds are set up to let you continue living in the home throughout the process. Exceptions may arise 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 kickoff meeting.

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

An ADU constructed with quality materials can be expected to last as long as the main residence — often get more info several decades with routine maintenance. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and comply with all local building codes to protect your investment for the long haul.

ADU Construction for Local Homeowners

The communities throughout San Jose provide a wide range of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as housing demand rises. Whether your property is near downtown San Jose, our team has project experience in the area.

San Jose's permitting office 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 team's knowledge of the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.

Schedule Your ADU Construction Planning Session Today

When you want to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we understand your vision and give you a realistic picture of what the project will involve.

Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. Building an ADU is a major decision — and we want to make sure it's the right one for you.

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