Brother & Brother Builders

Expand Your Home with Expert 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 provides 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 craftsmanship and integrity.

The popularity of ADU construction has increased significantly in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property functions.

At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering considerations, and the planning steps that make an ADU truly livable. Should you want to learn 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 involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including a kitchen, bathroom, sleeping area, and its own access point — that is located on the same parcel as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.

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 local building department. Once approvals are in place, ADU construction enters the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit connected to or independent of 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 align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.

Key Benefits ADU Construction

• Higher Resale Potential — ADU construction contributes significant 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.
• Space for Loved Ones — ADU construction offers family members a comfortable home of their own without moving to another neighborhood.
• Personalized Layouts — From open-plan one-bedrooms, ADU construction is adaptable to the intended occupant's lifestyle.
• Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, which aligns with sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
• Long-Term Investment Security — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Initial Property Assessment and Feasibility Review — Our team visits 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. Custom Design and Architectural Planning — Our design team create detailed floor plans based on your goals. Every square foot is planned to maximize function and livability.
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, the build starts. This involves leveling and prepping the ground, pouring the concrete foundation, and establishing utility connections.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU takes its visible shape.
6. Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. All work is inspected at designated stages throughout ADU construction.
7. Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.

Who Is a Good Candidate for ADU Construction?

Homeowners who benefit most from ADU construction often belong to a few clear categories. If you are a homeowner with available square footage under zoning rules, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families supporting elderly parents.

You may also be someone who needs a dedicated professional workspace and wants a detached creative or business space that doesn't interfere with your family's daily life. Property investors and rental owners who already own residential properties are also well suited for ADU construction, since the long-term value is proven.

Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may face additional constraints. Our team can assess each property case by case to provide realistic options.

ADU Construction Common Questions Answered

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

The complete duration for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions often finish in the lower end of the range, while larger new construction ADUs take longer to complete.

What does ADU construction cost in San Jose?

Pricing depends on many factors based on whether it's a conversion or new construction. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.

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

The day-to-day impact 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 create short-term inconveniences during certain phases of construction. We provide advance notice about upcoming work and timelines.

Do I need to vacate the property during ADU construction?

Generally speaking, you are not required to vacate your house during ADU construction. The vast majority of projects are set up to let you stay in your primary unit throughout the construction timeline. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.

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

An ADU constructed with quality materials should last as long as your primary home — often several decades with routine maintenance. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to protect your investment for the long haul.

ADU Construction for San Jose Homeowners

San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Residents in the Rose Garden district often discover their properties are well configured for ADU builds. Communities around the Capitol Expressway corridor have seen growing ADU activity 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 has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our team's knowledge of the San Jose permitting environment means more accurate timelines and budgets read more from design through the final walkthrough.

Start Your ADU Construction Planning Session Today

When you want to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our builders provide proven skills in ADU construction across a wide range of project types — from modest studio builds to fully independent secondary homes. The process begins with a comprehensive site assessment where we understand your vision and give you a realistic picture of what the project will involve.

Reach out to our team to set up your consultation. No matter where you are in the decision-making process, our team is happy to walk through your options, review completed projects and make sure you feel confident before committing. ADU construction is a significant investment — and our goal is to ensure it delivers real value.

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