Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with skill and transparency.
The popularity of ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have encouraged 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 job. Our team understands the local permitting process, the engineering details, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction refers to the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring 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 interior space reconfigurations.
Mechanically, the process begins with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a self-contained residence without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to your specific needs.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what's possible before any resources go toward planning.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints based on your goals. 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. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are issued, physical construction begins. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Framing is completed followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who needs a dedicated professional workspace and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who want to maximize their land are also a natural fit for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction typically 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 local permitting timelines. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Straightforward interior conversions often finish in the lower end of the range, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Budget requirements differ based on the type and size of the ADU. For most projects in this region, ADU construction typically ranges from $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. A precise cost projection can only be given after completing a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you do not need to vacate your house during ADU construction. Most builds are 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 require short-term access disruption. Our project managers will walk you through any potential disruptions during the planning phase.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials should last as long as your primary home — often several decades with routine maintenance. Durability depends to the systems installed, whether the unit website is properly cared for, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity 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 diverse mix of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road 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.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit corridors can impact the design approach for a given ADU project. Our familiarity with the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.
Book Your ADU Construction Consultation Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. We bring proven skills in ADU construction for many different project types — from simple garage conversions to fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to begin the conversation. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and help you take the next step. ADU construction is a significant investment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632