Brother & Brother Builders

Expand Your Home 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 creates a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with precision and transparency.

The popularity of ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property works.

At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the planning steps that make an ADU functional. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to know.

What Is ADU Construction?

ADU construction refers to the process of engineering, filing for, and completing 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 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 work starts with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.

The difference between a good and a great ADU build is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we bring to full custom home projects.

Key Benefits ADU Construction

• Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
• Revenue Generation — 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 gives aging parents a self-contained residence without leaving the property.
• Customization Options — From modern studio layouts, ADU construction may be customized to your specific needs.
• Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
• Sustainable Land Use — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• Lasting Financial Benefit — A well-built ADU continues to produce returns for many years and generates both usable housing and equity growth.

The ADU Construction Journey Step by Step

1. Initial Property Assessment and Feasibility Review — Our experts review 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. Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
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, responding to review feedback promptly.
4. Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
5. Shell Construction and Exterior Finishing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. This phase, the ADU becomes recognizable as a structure.
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 designated stages throughout ADU construction.
7. Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.

Who Is a Right Fit for ADU Construction?

Property owners who are best suited from ADU construction generally fit within a here few recognizable groups. If you have a residential property with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.

You may also be someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.

Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may require additional review. Our team can assess each property individually and honestly to advise you on what's feasible.

ADU Construction Frequently Asked Questions

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

The full timeline 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 two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units 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 cost in San Jose?

Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects often come in under, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a formal feasibility evaluation.

Is ADU construction intrusive while it's underway?

The level of disruption depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Garage conversions or attached additions may involve some shared wall work during certain phases of construction. Our team communicates clearly about any phases that may affect your routine.

Do I need to vacate the property during ADU construction?

In most cases, you won't have to vacate your house during ADU construction. Most builds 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. Our project managers will flag these situations during the pre-construction consultation.

How long will an ADU built through professional ADU construction last?

A well-built ADU can be expected to last as long as any standard residential structure — indefinitely with proper upkeep. Durability depends to the standard of construction, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Our builds use high-quality components and comply with all local building codes to protect your investment for the long haul.

ADU Construction for Local Homeowners

Residential areas across San Jose present a diverse mix of property types that are well suited 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 families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.

Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. 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 smoother project delivery from kickoff through certificate of occupancy.

Schedule Your ADU Construction Planning Session Today

When you want to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer years of hands-on experience in ADU construction across a wide range of project types — from modest studio builds to large custom detached cottages. The process begins with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.

Reach out to our team to set up your consultation. No matter where you are in the decision-making process, we're glad to answer questions, share examples of our work and give you the clarity you need to move forward. 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