Brother & Brother Builders

Transform Your Property with Professional ADU Construction

Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates 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 bring these projects to life with craftsmanship and integrity.

The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.

At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering requirements, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide will walk you through everything you need to know.

What Is the ADU Construction Process?

ADU construction refers to the process of designing, permitting, and building 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 entryway — 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 basement or interior conversions.

Mechanically, the process begins with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction enters the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit adjacent to or detached from your main home.

What sets quality ADU construction apart is the level of craftsmanship at every stage. Materials must be selected to complement the existing structure. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.

Key Reasons to Choose ADU Construction

• Boosted Home Equity — ADU construction delivers real 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.
• Multi-Generational Living — ADU construction offers family members a comfortable home of their own without moving to another neighborhood.
• Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to your household's priorities.
• Simplified Regulatory Path — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and less expensive than ever before.
• Sustainable Land Use — Building an ADU works within your current footprint instead of requiring new development, which supports broader sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.

The ADU Construction Journey 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 stage clarifies exactly what ADU types will work before any money is spent on design.
2. Blueprint Development and Layout Design — Licensed architects and designers create precise architectural drawings tailored to your needs. Every square foot is planned to create practical, comfortable living.
3. Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
4. Site Preparation and Foundation Work — Once permits are issued, the build starts. This includes grading the site, completing foundation work, and setting up utilities.
5. Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. This phase, 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. Every system is reviewed at designated stages throughout ADU construction.
7. Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.

Who Is a Right Fit for ADU Construction?

People who see the greatest return from ADU construction often belong to a few clear categories. If you are a homeowner 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 accommodating adult children who need housing.

You may also be someone who needs a dedicated professional workspace 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 rental income frequently offsets build costs.

Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Brother & Brother Builders reviews each property case by case to recommend the right path forward.

ADU Construction Common Questions Answered

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

The total process for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built 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 larger new construction ADUs require more time.

What does ADU construction cost in San Jose?

Costs vary widely 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. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be developed after a formal feasibility evaluation.

Is ADU construction intrusive while it's underway?

The day-to-day impact depends on whether you're converting existing space or building new. New construction more info in the rear yard are typically less disruptive, since the construction zone is separate. Garage conversions or attached additions 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 do not need to vacate your house during ADU construction. Most job sites are structured to allow you remain on the property throughout the construction timeline. Exceptions may arise if major utility upgrades affect the main house in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.

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

Any ADU built to code with professional oversight should last as long as any standard residential structure — often several decades with routine maintenance. Durability depends to the systems installed, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and follow all code requirements to protect your investment for the long haul.

ADU Construction for Local Homeowners

The communities throughout San Jose provide a variety 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. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.

The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. 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 fewer surprises from the first meeting to the final inspection.

Start Your ADU Construction Consultation Today

Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction across a wide range of project types — from modest studio builds to large custom detached cottages. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what's achievable.

Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, our team is happy to 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