Unlock New Space with Expert ADU Construction
Property owners throughout San Jose, CA are realizing 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 supported hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
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 apply deep hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU truly livable. Should you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
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 fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, everything kicks off with a detailed site assessment, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit attached to or separate from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen 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 Benefits 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.
- Housing for Extended Family — ADU construction offers family members a private, independent living space without leaving the property.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process 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.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what can be built before any time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints reflecting your priorities. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, on-site work kicks off. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A final city inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you own a single-family home with available square footage under zoning rules, you're already well-positioned. Homeowners hoping to offset mortgage costs 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 needs a dedicated professional workspace and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also well suited for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our team can assess each property on its own merits to advise you on what's feasible.
ADU Construction FAQ
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. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. 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 key milestones. 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 won't have to vacate your house during ADU construction. Most builds are designed so that you stay in your primary unit throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight can be expected to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a diverse mix of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved 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.
Start Your ADU Construction Planning Session Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer years of hands-on experience in ADU construction for many different project types — from modest studio builds to fully independent secondary homes. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest more info assessment of what's achievable.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, we're glad to walk through your options, review completed projects and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632