Brother & Brother Builders

Expand Your Home with Professional 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 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 skill and transparency.

The popularity of ADU construction has surged in recent years, and it's not hard to see why. 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 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 serves your household.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering details, and the design choices that make an ADU functional. When you're ready to explore what ADU construction could mean 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 complete living space — equipped with a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.

Mechanically, the process begins with a detailed site assessment, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction enters the physical build phase — website which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit connected to or independent of your main home.

The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.

Key Advantages ADU Construction

• Boosted Home Equity — ADU construction contributes significant market value to your property, often generating strong equity gains 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 gives aging parents a private, independent living space without moving to another neighborhood.
• Customization Options — From modern studio layouts, ADU construction may be customized to your specific needs.
• Streamlined Approval Process — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and less expensive than ever before.
• Efficient Use of Your Lot — Building an ADU uses your existing lot 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 many years and generates 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 phase answers exactly what's possible before any time is invested in drawings.
2. Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Every square foot is planned to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Our team handles all submissions on your behalf, addressing any city comments promptly.
4. Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This includes grading the site, laying the structural base, and running initial plumbing and electrical conduits.
5. Shell Construction and Exterior Finishing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
6. Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at required milestones throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A closing municipal review grants legal occupancy status and the ADU is ready for use.

Who Is a Right Fit for ADU Construction?

Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.

ADU construction also suits someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also well suited for ADU construction, since the return on investment is well-documented.

Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property individually and honestly to advise you on what's feasible.

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. City review on its own can take two to four months in San Jose, so planning ahead matters. Straightforward interior conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.

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 detached new build. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be produced following a full site assessment.

Is ADU construction disruptive while it's underway?

The level of disruption depends on whether you're converting existing space or building new. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about upcoming work and timelines.

Do I need to move out during ADU construction?

In most cases, you are not required to vacate your main home during ADU construction. Most builds are set up to let you stay in your primary unit throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers 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?

A well-built ADU should last as long as any standard residential structure — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components and build to current California residential standards to ensure lasting performance.

ADU Construction for San Jose Homeowners

The communities throughout San Jose provide a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team knows the permitting landscape well.

Local regulatory bodies in this area applies particular standards for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means fewer surprises from design through the final walkthrough.

Start Your ADU Construction Planning Session Today

Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction across a wide range of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a comprehensive site assessment where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.

Reach out to our team to begin the conversation. Whether you're in the early stages of planning, we enjoy answer questions, share examples of our work and give you the clarity you need to move forward. 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