Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother read more Builders has supported hundreds of local homeowners bring these projects to life with precision and transparency.
The interest in ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. Whether you're building 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 understands the local permitting process, the engineering considerations, and the design choices that make an ADU beautiful. If you've been thinking 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 describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete 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 basement or interior conversions.
Mechanically, the work starts with a detailed site assessment, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit connected to or independent of your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Materials must be selected to complement the existing structure. 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 apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often increasing appraised value substantially 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.
- Space for Loved Ones — ADU construction provides adult children a comfortable home of their own without leaving the property.
- Design Flexibility — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Streamlined Approval Process — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of expanding urban sprawl, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
- Blueprint Development and Layout Design — Our design team create precise architectural drawings reflecting your priorities. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are issued, the build starts. This involves leveling and prepping the ground, pouring the concrete foundation, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to the agreed design. A last official inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few common profiles. If you have a residential property with available square footage under zoning rules, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is 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 want to maximize their land are also prime candidates 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 face additional constraints. Brother & Brother Builders reviews each property individually and honestly to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction usually 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 how quickly approvals come through. Permitting alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Interior conversions may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. Most builds are set up to let you continue living in the home throughout the build. There are edge cases if major utility upgrades affect the main house in ways that briefly affect habitability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials can be expected to last as long as your primary home — typically 50 years or more. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a wide range of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as housing demand rises. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit corridors can impact the design approach for a given ADU project. Our familiarity with these local conditions means fewer surprises from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we understand your vision and give you a realistic picture of what's achievable.
Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and make sure you feel confident before committing. 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