Expert ADU Construction Services for Homeowners

Unlock New Space with Expert 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 creates a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and care.

The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property works.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering considerations, and the design choices that make an ADU functional. 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 ADU Construction?

ADU construction refers to the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — equipped with a kitchen, bathroom, sleeping area, and its own access point — that exists on the same lot 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 permits are secured, ADU construction moves into 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 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 read more every ADU construction job with the same professional rigor we bring to full custom home projects.

Key Advantages ADU Construction

• Increased Property Value — ADU construction contributes significant 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.
• Housing for Extended Family — ADU construction offers family members a comfortable home of their own without leaving the property.
• Design Flexibility — From two-bedroom configurations, ADU construction may be customized to the intended occupant's lifestyle.
• Streamlined Approval Process — Recent state legislation has minimized the red tape associated with ADU construction, making the process that is faster and less expensive than ever before.
• Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, which contributes to sustainability goals.
• Privacy for All Residents — 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 decades, providing both functional space and financial upside.

The ADU Construction Journey Step by Step

1. Site Evaluation and Zoning Analysis — 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 ADU types will work before any money is spent on design.
2. Architectural Drafting and Space Planning — Licensed architects and designers create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to maximize function and livability.
3. Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
4. Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This includes grading the site, laying the structural base, and setting up utilities.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
6. Interior Systems and Infrastructure — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A closing municipal review confirms the unit is code-compliant and the unit is officially approved for use.

Who Is a Good Candidate for ADU Construction?

Property owners who are best suited from ADU construction often belong to a few clear categories. 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 financially driven ADU construction clients, along with families accommodating adult children who need housing.

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 well suited for ADU construction, since the long-term value is proven.

Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property on its own merits to recommend the right path forward.

ADU Construction Frequently Asked Questions

How long does ADU construction usually 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 city review schedules. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs require more time.

What does ADU construction typically cost?

Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions are generally priced lower, sometimes between $75,000 and $140,000. An accurate budget can only be given after completing a formal feasibility evaluation.

Is ADU construction disruptive while it's underway?

The day-to-day impact depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may create short-term inconveniences during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about upcoming work and timelines.

Do I need to move out during ADU construction?

In most cases, you won't have to vacate your primary residence during ADU construction. The vast majority of 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 briefly affect habitability. The team at Brother & Brother Builders 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 — often several decades with routine maintenance. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.

ADU Construction for Local Homeowners

Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team has likely worked nearby.

San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from kickoff through certificate of occupancy.

Book Your ADU Construction Planning Session Today

Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction across a wide range of project types — from small attached additions to fully independent secondary homes. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what ADU construction on your property will look like.

Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we enjoy walk through your options, review completed projects and help you take the next step. This type of project is a meaningful commitment — and we're committed to helping you get it right.

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