Expand Your Home with Professional 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 opens the door to a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and care.
The demand for ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. Whether you're building 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 bring years of hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU read more construction could look like on your property, this guide explains everything you need to know.
What Is ADU Construction?
ADU construction refers to 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 entryway — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, 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, blueprints are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Materials must be selected to match the primary home's aesthetic. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor 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 generating strong equity gains when it's time to sell.
- Revenue Generation — 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 comfortable home of their own without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction may be customized to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has reduced 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 aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings reflecting your priorities. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. 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 covers land preparation, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by insulation, sheathing, and exterior cladding. 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.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A final city inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few recognizable groups. If you are a homeowner with a backyard, garage, or basement that could be converted, 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.
ADU construction also suits someone who works from home and wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who are building a portfolio are also a natural fit for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may face additional constraints. Brother & Brother Builders reviews each property case by case to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and how quickly approvals come through. Permitting alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions often finish in the lower end of the range, while multi-room detached cottages require more time.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. An accurate budget can only be produced following a full site assessment.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. New construction in the rear yard 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 certain phases of construction. Our team communicates clearly about any phases that may affect your routine.
Do I need to move out during ADU construction?
For the majority of homeowners, you are not required to vacate your main home during ADU construction. Most builds are structured to allow you continue living in the home throughout the process. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. Our project managers will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components and follow all code requirements to deliver a structure that stands the test of time.
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 often discover their properties are well configured for ADU builds. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office follows defined procedures for ADU construction that our team navigates routinely. 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 smoother project delivery from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to move forward with ADU construction, 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 fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation 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 begin the conversation. No matter where you are in the decision-making process, our team is happy to walk through your options, review completed projects and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632