Brother & Brother Builders

Transform Your Property with Expert ADU Construction

Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with skill and care.

The popularity of ADU construction has surged in recent years, and it's no mystery. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have supported 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 provides increased control over how your property serves your household.

At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering details, and the design choices that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide covers everything you need to know.

What Is an ADU Build?

ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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 detailed site assessment, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit attached to or separate from your main home.

What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical 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 Benefits ADU Construction

• Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
• Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
• Space for Loved Ones — ADU construction provides adult children a self-contained residence without moving to another neighborhood.
• Customization Options — From two-bedroom configurations, ADU construction may be customized to the intended occupant's lifestyle.
• Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
• Efficient Use of Your Lot — Building an ADU uses your existing lot instead of consuming open land, which aligns with sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
• Durable Return on Investment — 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. Site Evaluation and Zoning Analysis — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any resources go toward planning.
2. Blueprint Development and Layout Design — Our design team create detailed floor plans reflecting your priorities. Every square foot is planned to maximize function and livability.
3. Permitting and City Approval — ADU construction in San Jose involves filing drawings 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 issued, physical construction begins. This includes grading the site, pouring the concrete foundation, and establishing utility connections.
5. Structural Framing and Weatherproofing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU transforms from a concept to a building.
6. MEP Systems Rough-In — Certified technicians 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. Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to the agreed design. A closing municipal review grants legal occupancy status and the unit is officially approved for use.

Who Is a Good Candidate for ADU Construction?

Homeowners who benefit most from ADU construction often belong to a few common profiles. If you have a residential property with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.

You may also be someone who works from home and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since rental income frequently offsets build costs.

Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property individually and honestly to advise you on what's feasible.

ADU Construction FAQ

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

The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. City review on its own can take a significant portion of the overall timeline in San Jose, so starting early is important. Smaller detached units can move faster, while larger new construction ADUs fall toward the upper end of the timeline.

What does ADU construction cost in San Jose?

Costs vary widely based on whether it's a conversion or new construction. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be given after completing a formal feasibility evaluation.

Is ADU construction disruptive while it's underway?

How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may create short-term inconveniences during specific stages like framing or MEP rough-in. Our team communicates clearly about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

In most cases, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you stay in your primary unit throughout the construction timeline. There are edge cases if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will flag these situations during the kickoff meeting.

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

Any ADU built to code with professional oversight can be expected to last as long as your primary home — often several decades with routine maintenance. 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 commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.

ADU Construction for San Jose Homeowners

Residential areas across San Jose present 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 have seen growing ADU activity as families expand. Whether your property is near downtown San Jose, our team has likely worked nearby.

The City of San Jose's building department has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit here corridors can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from the first meeting to the final inspection.

Start Your ADU Construction Assessment Today

If you're ready to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to large custom detached cottages. Our approach opens with a thorough and honest property review where we listen to your goals and share clear expectations of what the project will involve.

Contact Brother & Brother Builders to set up your consultation. Whether you're in the early stages of planning, we're glad to 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