Expand Your Home 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 opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with craftsmanship and integrity.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. If you're planning a website detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering requirements, and the planning steps that make an ADU functional. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is ADU Construction?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own access point — that is located on the same parcel 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 comprehensive review of your lot, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction enters the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Components should be specified to align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same professional rigor we use on major custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often returning more than the build cost 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 offers family members a comfortable home of their own without losing proximity to the family.
- Design Flexibility — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — 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.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of requiring new development, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Licensed architects and designers create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are issued, physical construction begins. This covers land preparation, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are installed and finished 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 often belong to a few common profiles. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who needs a dedicated professional workspace and wants a detached creative or business space that remains away 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 return on investment is well-documented.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our experts will evaluate each property case by case to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take several months in San Jose, so starting early is important. Straightforward interior conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions are generally priced lower, sometimes in the $80,000 to $150,000 range. An accurate budget 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. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
In most cases, you do not need to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. 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 is designed to last as long as any standard residential structure — typically 50 years or more. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety 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. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
The City of San Jose's building department applies particular standards 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. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.
Start Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to fully independent secondary homes. Every project starts with a comprehensive site assessment where we understand your vision and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to begin the conversation. Whether you're in the early stages of planning, we enjoy walk through your options, review completed projects and help you take the next step. ADU construction is a significant investment — 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