Transform Your Property with Professional ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides 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 bring these projects to life with precision and integrity.
The demand for ADU construction has increased significantly 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 address housing needs. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is an ADU Build?
ADU construction describes 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 — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the process begins with a comprehensive review of your lot, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Materials must be selected to complement the existing structure. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders treats each project with the same professional rigor we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU is leasable 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.
- Design Flexibility — From modern studio layouts, ADU construction is adaptable to your specific needs.
- Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of requiring new development, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU continues to produce returns for decades, providing both usable housing and equity growth.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings reflecting your priorities. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — 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.
- Site Preparation and Foundation Work — Once permits are granted, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. This phase, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to the approved plan. A last official inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few common profiles. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who runs a small business and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since the return on investment is well-documented.
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 on its own merits to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually 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 several months in San Jose, so starting early is important. Smaller detached units can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since the construction zone is separate. Interior conversions may require temporary access during certain phases of construction. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home during ADU construction?
In most cases, you are not required to vacate your main home during ADU construction. Most job sites are click here designed so that you continue living in the home throughout the process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU should last as long as the main residence — often several decades with routine maintenance. Durability depends to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. We select high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, 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 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 the first meeting to the final inspection.
Start Your ADU Construction Consultation Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.
Get in touch with our office to begin the conversation. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. 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