Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
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 add these secondary units, and local municipalities like San Jose have supported the trend as a way to expand the housing supply. Whether you want to build 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 project. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide will walk you through 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 — 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 interior space reconfigurations.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders treats each project with the same technical discipline we bring to full custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has cut down 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 uses your existing lot instead of expanding urban sprawl, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Space is thoughtfully allocated to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This covers land preparation, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. At this stage, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Inspections are completed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are installed and finished to your specifications. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you have a residential property with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who runs a small business and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also prime candidates for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our team can assess each property on its own merits to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. Permitting alone can take two to four months in San Jose, so planning ahead matters. Straightforward interior conversions may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction usually run in terms of budget?
Costs vary widely based on the type and size of the ADU. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be given after completing a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. New construction in the rear yard are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your house during ADU construction. Most builds are designed so that you stay in your primary unit throughout the build. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will discuss these scenarios 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 your primary home — typically 50 years or more. Longevity is tied to here the systems installed, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor have seen growing ADU activity as housing demand rises. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Consultation Today
When you want to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our builders provide licensed expertise in ADU construction for many different project types — from modest studio builds to fully independent secondary homes. Our approach opens with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to schedule a site visit. Even if you're just exploring the idea, we enjoy 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