Unlock New Space with Professional ADU Construction
Families in 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 generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with craftsmanship and care.
The popularity of ADU construction has surged in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. 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 works.
At Brother & Brother Builders, we draw on extensive 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 truly livable. Should more info you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction involves 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 — equipped with a kitchen, bathroom, sleeping area, and its own entrance — 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 work starts with a thorough property evaluation, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.
Key Benefits 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.
- Revenue Generation — 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 provides adult children a self-contained residence without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the red tape 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 contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our team visits 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 money is spent on design.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This includes grading the site, completing foundation work, 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 transforms from a concept to a building.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are placed and inspected to the agreed design. A last official inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few recognizable groups. If you own a single-family home with available square footage under zoning rules, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who needs a dedicated professional workspace and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units often finish in the lower end of the range, while multi-room detached cottages take longer to complete.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on project complexity and finishes selected. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are typically less disruptive, since work happens away from the main house. Interior conversions may create short-term inconveniences during certain phases of construction. Our team communicates clearly about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
Generally speaking, you do not need to vacate your house during ADU construction. Most job sites are designed so that you remain on the property throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials can be expected to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Consultation Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. The process begins with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what's achievable.
Contact Brother & Brother Builders to begin the conversation. No matter where you are in the decision-making process, we enjoy answer questions, share examples of our work 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