Brother & Brother Builders

Expand Your Home with Quality ADU Construction

Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and transparency.

The interest in ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has simplified the process read more for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.

At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the design choices that make an ADU beautiful. If you've been thinking about what ADU construction could mean for your property, this guide explains everything you need to know.

What Is the ADU Construction Process?

ADU construction involves 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 — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.

Mechanically, the work starts with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction moves into the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. 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 treats each project with the same technical discipline we apply to large-scale custom home projects.

Key Benefits ADU Construction

• Higher Resale Potential — 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 may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Multi-Generational Living — ADU construction offers family members a comfortable home of their own without losing proximity to the family.
• Design Flexibility — From modern studio layouts, ADU construction is adaptable to your specific needs.
• Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, making the process that is faster and more affordable than ever before.
• Efficient Use of Your Lot — 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 occupants have full privacy.
• Long-Term Investment Security — 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's possible before any resources go toward planning.
2. Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
3. Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
4. Excavation and Foundation Installation — Once permits are approved, the build starts. This includes grading the site, pouring the concrete foundation, and setting up utilities.
5. Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
6. MEP Systems Rough-In — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A closing municipal review issues the certificate of occupancy 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 typically fall into a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.

You may also be someone who runs a small business and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.

Situations where ADU construction may not be the best first step include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our team can assess each property on its own merits to provide realistic options.

ADU Construction Common Questions Answered

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

The full timeline for ADU construction commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take a significant portion of the overall timeline in San Jose, so starting early is important. Smaller detached units can move faster, while custom detached builds 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. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a formal feasibility evaluation.

Is ADU construction disruptive while it's underway?

The level of disruption depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. Our team communicates clearly about what to expect at each stage.

Do I need to leave my home during ADU construction?

For the majority of homeowners, you do not need to vacate your primary residence during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the process. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will flag these situations during the planning phase.

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

A well-built ADU can be expected to last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and comply with all local building codes to protect your investment for the long haul.

ADU Construction for San Jose Homeowners

The communities throughout San Jose provide a variety 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. The Berryessa area are increasingly popular for ADU construction as housing demand rises. Whether your property is near downtown San Jose, our team knows the permitting landscape well.

San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from kickoff through certificate of occupancy.

Schedule Your ADU Construction Consultation Today

If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction for many different project types — from simple garage conversions to fully independent secondary homes. The process begins with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture 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 discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a major decision — and our goal is to ensure it delivers real value.

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