Unlock New Space with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with craftsmanship and transparency.
The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. 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 bring years of hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the design choices that make an ADU truly livable. When you're ready to explore what ADU construction could look like on your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction refers to the process of engineering, filing for, and completing 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 entryway — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit connected to or independent of your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — 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 your household's priorities.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of requiring new development, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU continues to produce returns for the long haul by offering both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — 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 can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Our design team create precise architectural drawings reflecting your priorities. Layouts are carefully considered 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. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This includes grading the site, completing foundation work, and establishing utility connections.
- 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.
- MEP Systems Rough-In — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A closing municipal review issues the certificate of occupancy 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 generally fit within a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners looking to generate income 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 runs a small business and wants a private work environment that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and city review schedules. Permitting alone can take two to four months in San Jose, so starting early is important. Straightforward interior conversions often finish in the lower end of the range, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on whether it's a conversion or new construction. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget 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 the project's location on your property. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may require temporary access during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your primary residence during ADU construction. Most builds are designed so that you continue living in the home throughout the build. Exceptions may arise 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 last?
A well-built ADU should last as long as any standard residential structure — often several decades with routine maintenance. Longevity is tied to the adu construction quality of materials used, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has likely worked nearby.
Local regulatory bodies in this area follows defined procedures 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 this region's building landscape 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 here to help. Our builders provide proven skills in ADU construction across a wide range of project types — from modest studio builds to multi-room backyard residences. Every project starts with a detailed, no-pressure consultation where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to schedule a site visit. Whether you're in the early stages of planning, we're glad to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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