Expand Your Home with Quality ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to 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 bring these projects to life with craftsmanship and integrity.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. If you're planning 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 apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering considerations, and the design choices that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — 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 below-grade dwelling units.
Mechanically, everything kicks off with a detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction enters 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.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Components should be specified to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.
Key Advantages 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.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction offers family members a comfortable home of their own without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of expanding urban sprawl, which supports broader 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 remains an asset for the long haul by offering both usable housing and equity growth.
The ADU Construction Procedure 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 stage clarifies exactly what can be built before any time is invested in drawings.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints based on your goals. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, the build starts. This covers land preparation, pouring the concrete foundation, and establishing utility connections.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A closing municipal review confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited 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 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 works from home and wants a private work environment that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited more info for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our team can assess each property on its own merits to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take several months in San Jose, so starting early is important. Straightforward interior conversions may complete more quickly, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions often come in under, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be produced following a full site assessment.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since work happens away from the main house. Interior conversions may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you are not required to vacate your primary residence during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the process. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials is designed to last as long as any standard residential structure — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use commercial-grade materials and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as housing demand rises. If you're located closer to Evergreen, our team has likely worked nearby.
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 this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Book Your ADU Construction Planning Session Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise 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 learn what you're trying to accomplish and share clear expectations of what ADU construction on your property will look like.
Reach out to our team to begin the conversation. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. 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