Expand Your Home with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a powerful 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 precision and transparency.
The popularity of ADU construction has increased significantly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering details, and the aesthetic decisions that make an ADU functional. When you're ready to explore 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 designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — including a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot 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, the process begins with a comprehensive review of your lot, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction moves into the physical build phase — which covers everything website from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. 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 bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a self-contained residence without losing proximity to the family.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction may be customized to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced the red tape associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process 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 can be built before any resources go toward planning.
- Blueprint Development and Layout Design — Our design team create precise architectural drawings based on your goals. Space is thoughtfully allocated to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. We manage this entire process on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This includes grading the site, laying the structural base, and setting up utilities.
- Shell Construction and Exterior Finishing — 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 plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are fitted and completed to your specifications. A final city inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you are a homeowner with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated 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 is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction usually run in terms of budget?
Costs vary widely based on project complexity and finishes selected. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. A detailed estimate can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive 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. Projects that connect to the main structure may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
In most cases, you are not required to vacate your house during ADU construction. Most job sites are structured to allow you remain on the property throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our construction supervisors will walk you through any potential disruptions during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight should last as long as your primary home — typically 50 years or more. Longevity is tied to the standard of construction, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for Local Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly 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 have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
The City of San Jose's building department follows defined procedures for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects and help you take the next step. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632