Expand Your Home with Expert ADU Construction
Property owners throughout San Jose, CA are discovering 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 guided hundreds of local homeowners see these visions to life with craftsmanship and transparency.
The demand for ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a garage check here conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU functional. 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 ADU Construction?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — 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 below-grade dwelling units.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans 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, roofing, plumbing, electrical, insulation. The result is a completely finished living unit attached to or separate from your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to align with the neighborhood's character. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction provides adult children a private, independent living space without leaving the property.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient 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 creates a truly separate unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both functional space and financial upside.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Experienced draftspeople create precise architectural drawings reflecting your priorities. 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 inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, the build starts. This includes grading the site, completing foundation work, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. At this stage, 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 operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A last official inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few clear categories. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already a strong candidate. 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.
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 already own residential properties are also a natural fit for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so starting early is important. Smaller detached units may complete more quickly, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are typically less disruptive, 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. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your primary residence during ADU construction. Most job sites are structured to allow you remain on the property throughout the process. Certain situations could require a brief departure 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 kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies commercial-grade materials and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are well suited for ADU construction. Residents in the Rose Garden district frequently see their parcels work well for both attached and detached projects. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team knows the permitting landscape well.
The City of San Jose's building department applies particular standards for ADU construction that our team navigates routinely. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our team's knowledge of the San Jose permitting environment means smoother project delivery from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. Our builders provide proven skills in ADU construction including all types of project types — from small attached additions to large custom detached cottages. The process begins with a thorough and honest property review where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.
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 give you the clarity you need to move forward. This type of project is a meaningful commitment — 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