Expand Your Home with Expert ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to 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 turn these plans to life with skill and integrity.
The popularity of ADU construction has surged in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to construct 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 provides increased control over how your property functions.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering details, and the aesthetic decisions that make an ADU functional. If you've been thinking about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction refers to 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 — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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 process begins with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction enters the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship 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 professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has reduced the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints based on your goals. Layouts are carefully considered to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This includes grading the site, completing foundation work, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. This phase, 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 operationally complete. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few recognizable groups. If you are a homeowner with enough lot space to meet setback requirements, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Landlords and real estate investors who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may require additional review. Our team can assess each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. City review on its own can take a significant portion of the overall timeline in San Jose, so starting early is important. Simpler garage conversions can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be developed after a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on the project's location on your property. Standalone ADU projects are typically less disruptive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during certain phases of construction. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you do not need to vacate your main home during ADU construction. Most builds are structured to allow you stay in your primary unit throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. Our construction supervisors will walk you through any potential disruptions 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 — typically 50 years or more. How long it lasts comes down to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and follow all code requirements 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 well suited for ADU construction. Residents in the Rose Garden district often discover their properties work well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across these local conditions means smoother project delivery from the first meeting to the final inspection.
Book Your ADU Construction Assessment Today
Should you be thinking about how get more info to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer licensed expertise in ADU construction including all types of project types — from modest studio builds to multi-room backyard residences. The process begins with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and help you take the next step. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632