Expand Your Home with Quality ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical 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 guided hundreds of local homeowners bring these projects to life website with craftsmanship and integrity.
The interest in ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU functional. Should you want to learn about what ADU construction could mean for your property, this guide will walk you through everything you need to know.
What Is the ADU Construction Process?
ADU construction involves 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 — featuring a kitchen, bathroom, sleeping area, and its own access point — that exists on the same lot 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, everything kicks off with a thorough property evaluation, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the local building department. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we bring to full custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Housing for Extended Family — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, 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 less expensive than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU remains an asset for decades, providing both functional space and financial upside.
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 step tells you exactly what can be built before any time is invested in drawings.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints reflecting your priorities. Every square foot is planned to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. All work is inspected at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to your specifications. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you own a single-family home with available square footage under zoning rules, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners who are building a portfolio are also a natural fit for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property case by case to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on the project's location on your property. New construction in the rear yard are usually easier to live alongside, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences 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 move out during ADU construction?
In most cases, you are not required to vacate your house during ADU construction. The vast majority of projects are structured to allow you continue living in the home throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems 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 remain in good condition?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties are well configured for ADU builds. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our team's knowledge of this region's building landscape means smoother project delivery from the first meeting to the final inspection.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction for many different project types — from modest studio builds to large custom detached cottages. The process begins with a comprehensive site assessment where we listen to your goals and share clear expectations of what's achievable.
Reach out to our team to set up your consultation. No matter where you are in the decision-making process, our team is happy to walk through your options, review completed projects and give you the clarity you need to move forward. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632