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 most practical investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with skill and transparency.

The popularity of ADU construction has increased significantly 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 supported the trend as a way to address housing needs. 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 functions.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU truly livable. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to know.

What Is the ADU Construction Process?

ADU construction refers to 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 exists on the same lot as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.

Mechanically, the process begins with a comprehensive review of your lot, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the city for permit approval. Once approvals are in place, 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 attached to or separate 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 match the primary home's aesthetic. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.

Key Advantages ADU Construction

• Increased Property Value — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
• Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Housing for Extended Family — ADU construction gives aging parents a self-contained residence without leaving the property.
• Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your specific needs.
• Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
• Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• Lasting Financial Benefit — A well-built ADU remains an asset for decades, providing both usable housing and equity growth.

The ADU Construction Process 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 step tells you exactly what's possible before any resources go toward planning.
2. Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Every square foot is planned to optimize daily use.
3. Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. Our team handles all submissions on your behalf, resolving any revision requests promptly.
4. Site Preparation and Foundation Work — Once permits are issued, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and setting up utilities.
5. Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU takes its visible shape.
6. Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are fitted and completed to the agreed design. 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?

People who see the greatest return from ADU construction often belong to a few common profiles. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.

ADU construction also suits someone who needs a dedicated professional workspace and here wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since rental income frequently offsets build costs.

Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may require additional review. Our team can assess each property case by case to recommend the right path forward.

ADU Construction Common Questions Answered

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

The complete duration for ADU construction commonly spans six to fourteen months, based on the project scope and local permitting timelines. Permitting alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while custom detached builds take longer to complete.

What does ADU construction usually run in terms of budget?

Budget requirements differ 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 fully custom construction. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a formal feasibility evaluation.

Is ADU construction difficult to live through while it's underway?

How much the build affects daily life depends on the project's location on your property. New construction in the rear yard are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during certain phases of construction. Our team communicates clearly about upcoming work and timelines.

Do I need to move out during ADU construction?

In most cases, you won't have 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 walk you through any potential disruptions during the kickoff meeting.

How long will an ADU built through professional ADU construction remain in good condition?

An ADU constructed with quality materials should last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the standard of construction, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Our builds use commercial-grade materials and build to current California residential standards to ensure lasting performance.

ADU Construction for San Jose Homeowners

The communities throughout San Jose provide a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their properties work well for both attached and detached projects. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.

The City of San Jose's building department has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey 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 kickoff through certificate of occupancy.

Start Your ADU Construction Assessment 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 licensed expertise in ADU construction for many different project types — from simple garage conversions to large custom detached cottages. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture of what ADU construction on your property will look like.

Get in touch with our office to set up your consultation. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. 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