Transform Your Property with Quality ADU Construction
Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with skill and transparency.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to construct 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 provides increased control over how your property serves your household.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering requirements, and the design choices that make an ADU functional. If you've been thinking about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to 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 — 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 below-grade dwelling units.
Mechanically, the work starts with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction enters the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — ADU construction contributes significant market value to your property, often returning more than the build cost 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, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — 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 money is spent on design.
- Custom Design and Architectural Planning — Licensed architects and designers create precise architectural drawings based on your goals. Layouts are carefully considered to create practical, comfortable living.
- 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, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. At this stage, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — 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.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A last official inspection confirms the unit is code-compliant 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 typically fall into a few clear categories. If you have a residential property 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 motivated ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who needs a dedicated professional workspace and wants a detached creative or business space 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 rental income frequently offsets build costs.
Those who should discuss alternatives first include properties with significant setback limitations. Sites with underground infrastructure conflicts may face additional constraints. Our team can assess each property case by case to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. Permitting alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while larger new construction ADUs require more time.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a full site assessment.
Is ADU construction disruptive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
Generally speaking, you do not need to vacate your house during ADU construction. Most builds are set up to let you continue living in the home throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight is designed to last as long as the main check here residence — often several decades with routine maintenance. Longevity is tied to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. We select residential-grade products rated for longevity and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a variety of property types that are perfectly suited 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 families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
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 affect how quickly permits are approved for a given ADU project. Our familiarity with the San Jose permitting environment means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer licensed expertise 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's achievable.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632