Unlock New Space with Professional 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 versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and integrity.
The popularity of ADU construction has increased significantly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to add 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 bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU functional. Should you want to learn about what ADU construction could look like on your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including 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 basement or interior conversions.
Mechanically, the work starts with a comprehensive review of your lot, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. 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 encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. 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 depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a comfortable home of their own without losing proximity to the family.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot 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 tenants live autonomously.
- Durable Return on Investment — A well-built ADU holds its value for the long haul by offering both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any resources go toward planning.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are granted, on-site work kicks off. This includes grading the site, completing foundation work, and setting up utilities.
- Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. At this stage, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A last official inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few recognizable groups. If you are a homeowner with available square footage under zoning rules, you're already a strong candidate. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who runs a small business and wants a separate office or studio space that doesn't interfere with your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include sites with unusual utility read more access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property case by case to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between 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 planning ahead matters. Straightforward interior conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. 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?
The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Interior conversions may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
In most cases, you won't have to vacate your house during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that briefly affect habitability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
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 quality of materials used, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select residential-grade products rated for longevity and build to current California residential standards to protect your investment for the long haul.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a wide range of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that our team navigates routinely. Proximity to transit corridors 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.
Book Your ADU Construction Consultation Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction including all types of project types — from modest studio builds to fully independent secondary homes. Every project starts with a comprehensive site assessment where we understand your vision and give you a realistic picture of what's achievable.
Get in touch with our office to set up your consultation. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities and make sure you feel confident before committing. 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