Brother & Brother Builders

Unlock New Space with Quality 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 creates a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and care.

The popularity of ADU construction has increased significantly 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 encouraged the trend as a way to expand the housing supply. Whether you're building 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 draw on extensive hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU functional. 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 the ADU Construction Process?

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 exists on the same lot 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 work starts with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit attached to or separate from your main home.

What sets quality ADU construction apart 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 built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale 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.
• Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
• Space for Loved Ones — ADU construction offers family members a private, independent living space without moving to another neighborhood.
• Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
• Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more affordable than ever before.
• Responsible Property Development — 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 produces a fully self-contained unit where tenants live autonomously.
• Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both functional space and financial upside.

The ADU Construction Procedure Step by Step

1. Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
2. Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to create practical, comfortable living.
3. Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, resolving any revision requests promptly.
4. Site Preparation and Foundation Work — Once permits are issued, the build starts. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
5. Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU transforms from a concept to a building.
6. Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to your specifications. A last official inspection grants legal occupancy status and the unit is officially approved for use.

Who Is a Strong Candidate for ADU Construction?

People who see the greatest return from ADU construction often belong to a few clear categories. If you have a residential property 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 motivated ADU construction clients, along with families navigating multigenerational living situations.

Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Landlords and real estate investors who want to maximize their land are also a natural fit for ADU construction, since rental income frequently offsets build costs.

Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. 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 usually runs between six to fourteen months, depending on design complexity and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while multi-room detached cottages take longer to complete.

What does ADU construction cost in San Jose?

Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a full site assessment.

Is ADU construction disruptive while it's underway?

The day-to-day impact depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. Projects that connect to the main structure may require temporary access during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about upcoming work and timelines.

Do I need to leave my home during ADU construction?

For the majority of homeowners, you won't have to vacate your house during ADU construction. The vast majority of more info projects are designed so that you remain on the property throughout the build. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will discuss these scenarios 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 is designed to last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use high-quality components and build to current California residential standards to deliver a structure that stands the test of time.

ADU Construction for San Jose 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 frequently see their parcels accommodate detached backyard units nicely. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has likely worked nearby.

San Jose's permitting office has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach 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 Assessment Today

Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our builders provide years of hands-on experience in ADU construction including all types of project types — from small attached additions to large custom detached cottages. Every project starts with a thorough and honest property review where we listen to your goals and share clear expectations of what's achievable.

Reach out to our team to schedule a site visit. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects and give you the clarity you need to move forward. ADU construction is a significant investment — 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