Brother & Brother Builders

Unlock New Space with Expert ADU Construction

Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and care.

The popularity of ADU construction has increased significantly in recent years, and it's website 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 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 draw on extensive hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could look like on your property, this guide explains 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 self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.

Mechanically, everything kicks off 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 moves into the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit attached to or separate from your main home.

What sets quality ADU construction apart is the depth of planning at every stage. Materials must be selected to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same professional rigor we bring to full custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction adds measurable 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, providing a consistent income stream for the homeowner.
• Housing for Extended Family — ADU construction gives aging parents a private, independent living space without moving to another neighborhood.
• Customization Options — From modern studio layouts, ADU construction can be tailored to your household's priorities.
• Streamlined Approval Process — Recent state legislation has reduced the permitting obstacles associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
• Efficient Use of Your Lot — Building an ADU uses your existing lot instead of requiring new development, which aligns with sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
• Long-Term Investment Security — A well-built ADU remains an asset for decades, providing both usable housing and equity growth.

The ADU Construction Procedure Step by Step

1. Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any resources go toward planning.
2. Custom Design and Architectural Planning — Our design team create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
3. Permit Submission and Municipal Review — 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, responding to review feedback promptly.
4. Site Preparation and Foundation Work — Once permits are issued, the build starts. This covers land preparation, pouring the concrete foundation, and setting up utilities.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU takes its visible shape.
6. Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the approved plan. A closing municipal review issues the certificate of occupancy and the ADU is ready for use.

Who Is a Strong Candidate for ADU Construction?

Property owners who are best suited from ADU construction typically fall into a few recognizable groups. If you are a homeowner with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.

Another strong candidate is someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners who want to maximize their land are also well suited for ADU construction, since the long-term value is proven.

Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may require additional review. Our team can assess each property case by case to recommend the right path forward.

ADU Construction FAQ

How long does ADU construction usually 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 local permitting timelines. The approval phase alone can take several months in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while multi-room detached cottages require more time.

What does ADU construction usually run in terms of budget?

Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be developed after a formal feasibility evaluation.

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

The level of disruption depends on whether you're converting existing space or building new. New construction in the rear yard are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

For the majority of homeowners, you won't have to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the process. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. Our construction supervisors will walk you through any potential disruptions during the kickoff meeting.

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

A well-built ADU is designed to last as long as any standard residential structure — typically 50 years or more. Durability depends to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. We select residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.

ADU Construction for San Jose Homeowners

Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area have found their lots work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team knows the permitting landscape well.

San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from kickoff through certificate of occupancy.

Schedule Your ADU Construction Consultation Today

If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. We bring proven skills in ADU construction including all types of project types — from modest studio builds to large custom detached cottages. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.

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. 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