Brother & Brother Builders

Unlock New Space with Expert ADU Construction

Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped 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 construct these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. Whether you want to build 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 apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could look like on your property, this guide explains everything you need to know.

What Is the ADU Construction Process?

ADU construction involves 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 — including a kitchen, bathroom, sleeping area, and its own entrance — 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 interior space reconfigurations.

Mechanically, the process begins with a thorough property evaluation, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.

What separates excellent ADU construction from an average project is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like plumbing and electrical 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

• 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 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 provides adult children a self-contained residence without leaving the property.
• Customization Options — From modern studio layouts, ADU construction is adaptable to your household's priorities.
• Streamlined Approval Process — Recent state legislation has reduced the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
• Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
• 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 Process Step by Step

1. Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what can be built before any resources go toward planning.
2. Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings tailored to your needs. Every square foot is planned to maximize function and livability.
3. Filing for Building Permits — ADU construction in San Jose demands documentation 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. Ground Prep and Structural Base — Once permits are approved, the build starts. This covers land preparation, pouring the concrete foundation, and setting up utilities.
5. Structural Framing and Weatherproofing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. This phase, the ADU takes its visible shape.
6. MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A final city inspection grants legal occupancy status and your new space is cleared for use.

Who Is a Strong Candidate for ADU Construction?

Property owners who are best suited from ADU construction often belong to a few common profiles. If you have a residential property with available square footage under zoning rules, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.

Another strong candidate is someone who runs a small business and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.

Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Our team can assess each property on its own merits to provide realistic options.

ADU Construction Frequently Asked Questions

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

The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take two to four months in San Jose, so beginning the process sooner here rather than later is wise. Simpler garage conversions often finish in the lower end of the range, while larger new construction ADUs fall toward the upper end of the timeline.

What does ADU construction typically cost?

Budget requirements differ based on whether it's a conversion or new construction. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. A detailed estimate can only be given after completing a thorough property review.

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

The level of disruption depends on the project's location on your property. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may create short-term inconveniences during key milestones. Our team communicates clearly about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

Generally speaking, you won't have to vacate your house during ADU construction. Most builds are set up to let you continue living in the home throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our construction supervisors will discuss these scenarios during the kickoff meeting.

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

An ADU constructed with quality materials can be expected to last as long as the main residence — typically 50 years or more. Longevity is tied to the standard of construction, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use commercial-grade materials and follow all code requirements to protect your investment for the long haul.

ADU Construction for Local Homeowners

San Jose's neighborhoods offer a diverse mix of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties are well configured for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as multigenerational living becomes more common. 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 our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.

Start Your ADU Construction Assessment Today

If you're ready to add an ADU to your property, 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. The process begins with a thorough and honest property review where we learn what you're trying to accomplish and share clear expectations of what's achievable.

Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and help you take the next step. 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