Transform Your Property with Expert ADU Construction
Property owners throughout 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 flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with precision and care.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. Whether you're building 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 build. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide will walk you through 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 self-contained living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — 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 basement or interior conversions.
Mechanically, the process begins with a detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Customization Options — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has reduced the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both usable housing and equity growth.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings tailored to your needs. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation 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 issued, physical construction begins. This includes grading the site, completing foundation work, and setting up utilities.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A last official inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few recognizable groups. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who runs a small business and wants a detached creative or business space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our experts will evaluate each property case by case to recommend the right path forward.
ADU Construction FAQ
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. Straightforward interior conversions often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Budget requirements differ based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be given after completing a thorough property review.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Interior conversions may require temporary access during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you won't have to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the process. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the systems installed, how well routine maintenance is performed, and if mechanical components are maintained on schedule. We select residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties work well for both attached and detached projects. Neighborhoods near Blossom Hill Road have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that experienced builders know well. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our familiarity with these local conditions means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
When you want to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction across a wide range of project types — from modest studio builds to fully independent secondary homes. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we're glad to answer questions, share examples of website our work and give you the clarity you need to move forward. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632