Expand Your Home with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a versatile 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 precision and transparency.
The demand for ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property functions.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including a kitchen, bathroom, sleeping area, and its own access point — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins with a detailed site assessment, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit connected to or independent of your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Components should be specified to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build 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.
- Monthly Cash Flow — 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 leaving the property.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction may be customized to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has cut down 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 uses your existing lot instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what ADU types will work before any money is spent on design.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints based on your goals. Every square foot is planned to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are issued, the build starts. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by weatherproofing and exterior finish materials. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A final city inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most 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 well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property on its own merits to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The here total process for ADU construction commonly spans six to fourteen months, based on the project scope and city review schedules. Permitting alone can take a significant portion of the overall timeline in San Jose, so starting early is important. Simpler garage conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Budget requirements differ based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Standalone ADU projects are typically less disruptive, since work happens away from the main house. Projects that connect to the main structure may require temporary access during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to vacate the property during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you remain on the property throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight is designed to last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the systems installed, whether the unit is properly cared for, and how proactively issues are resolved over time. We select residential-grade products rated for longevity 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. Property owners near the Almaden Valley area have found their lots work well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.
Start Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU construction across a wide range of project types — from modest studio builds to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632