Unlock New Space with Professional 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 opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with precision and care.
The demand for ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to add 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 draw on extensive hands-on experience to every ADU construction project. Our team knows the San Jose building codes, get more info the engineering details, and the aesthetic decisions that make an ADU beautiful. When you're ready to explore what ADU construction could do for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the work starts with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the local building department. Once permits are secured, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached 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 HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a self-contained residence without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, making the process 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 expanding urban sprawl, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU remains an asset for many years and generates both functional space and financial upside.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess 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.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans reflecting your priorities. Layouts are carefully considered to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, the build starts. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A closing municipal review issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. 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.
You may also be someone who works from home and wants a detached creative or business space that remains away from 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 return on investment is well-documented.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Sites with underground infrastructure conflicts may face additional constraints. Our team can assess each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. Permitting alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction cost in San Jose?
Budget requirements differ 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. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be produced following a full site assessment.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are typically less disruptive, since work happens away from the main house. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to move out during ADU construction?
In most cases, you do not need to vacate your main home during ADU construction. Most builds are designed so that you remain on the property throughout the build. Certain situations could require a brief departure 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 planning phase.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU can be expected to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies commercial-grade materials 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 perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department applies particular standards for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from design through the final walkthrough.
Start Your ADU Construction Consultation Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our builders provide years of hands-on experience 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 understand your vision and give you a realistic picture of what's achievable.
Contact Brother & Brother Builders to begin the conversation. 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 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