Transform Your Property with Expert ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a versatile new living space on your existing property — whether you want to house a more info family member. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with craftsmanship and care.
The demand for 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 want to build 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 project. Our team knows the San Jose building codes, the engineering requirements, and the planning steps that make an ADU beautiful. 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 the ADU Construction Process?
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 can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the work starts with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction moves into the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Materials must be selected to align with the neighborhood's character. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same technical discipline we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction adds measurable 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, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a self-contained residence without leaving the property.
- Customization Options — From modern studio layouts, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced the barriers and delays 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 consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU remains an asset for the long haul by offering both functional space and financial upside.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create detailed floor plans tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU fully functional. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to the approved plan. A final city inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few clear categories. If you have a residential property with available square footage under zoning rules, you're already well-positioned. 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 detached creative or business space that doesn't interfere with your family's daily life. Real estate-minded homeowners who want to maximize their land are also well suited for ADU construction, since rental income frequently offsets build costs.
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 need a modified approach. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase 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 larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
The level of disruption depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
In most cases, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow you continue living in the home throughout the process. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. Our construction supervisors will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight can be expected to last as long as the main residence — often several decades with routine maintenance. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
The City of San Jose's building department 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 more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is ready to guide you. We bring years of hands-on experience in ADU construction across a wide range of project types — from modest studio builds to fully independent secondary homes. The process begins with a detailed, no-pressure consultation where we listen to your goals and share clear expectations of what ADU construction on your property will look like.
Contact Brother & Brother Builders to begin the conversation. No matter where you are in the decision-making process, our team is happy to discuss timelines, costs, and design possibilities 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