Unlock New Space with Quality ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to 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 craftsmanship and integrity.
The popularity of ADU construction has increased significantly 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 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 considerations, and the aesthetic decisions that make an ADU functional. 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 designing, permitting, and building 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 access point — 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 interior space reconfigurations.
Mechanically, the process begins with a thorough property evaluation, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction enters the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Components should be specified to complement the existing structure. 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 bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a self-contained residence without losing proximity to the family.
- Customization Options — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, making the process that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Durable Return on Investment — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — 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 resources go toward planning.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are granted, the build starts. This includes grading the site, laying the structural base, and setting up utilities.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few common profiles. If you own a single-family home 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.
You may also be someone who runs a small business and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Very small lots or properties with easements may need a check here modified approach. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and local permitting timelines. Permitting alone can take several months in San Jose, so starting early is important. Simpler garage conversions can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be given after completing a thorough property review.
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 the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during specific stages like framing or MEP rough-in. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. Most job sites are designed so that you remain on the property 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 flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the standard of construction, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team knows the permitting landscape well.
San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach 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.
Start Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. We bring licensed expertise in ADU construction including all types of project types — from small attached additions to large custom detached cottages. Our approach opens with a detailed, no-pressure consultation where we understand your vision and give you a realistic picture of what's achievable.
Get in touch with our office to begin the conversation. Whether you're in the early stages of planning, our team is happy to answer questions, share examples of our work and make sure you feel confident before committing. Building an ADU is a major decision — 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