Brother & Brother Builders

Expand Your Home with Expert ADU Construction

Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest 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 supported hundreds of local homeowners see these visions to life with skill and integrity.

The interest in ADU construction has grown rapidly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have supported 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 gives you more control over how your property serves your household.

At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering details, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.

What Is an ADU Build?

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 — featuring a kitchen, bathroom, sleeping area, and its own entrance — that is located on the same parcel as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.

Mechanically, the work starts with a comprehensive review of your lot, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the city for permit approval. Once approvals are in place, 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 connected to or independent of your main home.

What sets quality ADU construction apart 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 designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same technical discipline we use on major custom home projects.

Key Benefits ADU Construction

• Boosted Home Equity — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
• Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
• Multi-Generational Living — 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.
• Faster Permitting in California — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Sustainable Land Use — Building an ADU works within your current footprint instead of expanding urban sprawl, which aligns with sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• Durable Return on Investment — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what ADU types will work before any resources go toward planning.
2. Blueprint Development and Layout Design — 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. We manage this entire process on your behalf, responding to review feedback promptly.
4. Ground Prep and Structural Base — Once permits are granted, the build starts. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
5. Shell Construction and Exterior Finishing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
6. Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A last official inspection grants legal occupancy status and the ADU is ready for use.

Who Is a Good Candidate for ADU Construction?

Homeowners who benefit most from ADU construction typically fall into 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 wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.

ADU construction also suits someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.

Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Our team can assess each property individually and honestly to recommend the right path forward.

ADU Construction Common Questions Answered

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

The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs take longer to complete.

What does ADU construction usually run in terms of budget?

Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a full site assessment.

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

The day-to-day impact depends on the project's location on your property. Detached backyard builds are generally the least intrusive, since the construction zone is separate. Interior conversions may create short-term inconveniences during certain phases of construction. We provide advance notice about what to expect at each stage.

Do I need to move out during ADU construction?

Generally speaking, you do not need to vacate your primary residence during ADU construction. Most job sites are set up to let you remain on the property throughout the construction timeline. Exceptions may arise if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will walk you through any potential disruptions during the pre-construction consultation.

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

An ADU constructed with quality materials should last as long as any standard residential structure — often several decades with routine maintenance. Durability depends to the systems installed, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and follow all code requirements to protect your investment for the long haul.

ADU Construction for San Jose Homeowners

Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as multigenerational living becomes more common. 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 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 familiarity with the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.

Schedule Your ADU Construction Assessment Today

Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is the team to call. Our experts offer years of hands-on experience in ADU construction including all types of project types — from small attached additions to fully independent secondary homes. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture of what the project will involve.

Get in touch with our office to begin the conversation. Even if you're just exploring the idea, we're glad to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a website major decision — 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