Transform Your Property with Quality ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and integrity.
The popularity of ADU construction has increased significantly in recent years, and it's easy to understand why. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the design choices that make an ADU functional. If you've been thinking about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
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 here its own entryway — that sits on the same property 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, the work starts with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Materials must be selected to complement the existing structure. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often increasing appraised value substantially 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.
- Space for Loved Ones — ADU construction gives aging parents a self-contained residence without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This phase answers exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Licensed architects and designers create precise architectural drawings tailored to your needs. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU becomes recognizable as a structure.
- 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 required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to your specifications. A last official inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few common profiles. 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 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 detached creative or business space that is distinct from your family's daily life. Landlords and real estate investors who want to maximize their land are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Brother & Brother Builders reviews each property individually and honestly to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. City review on its own can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while multi-room detached cottages require more time.
What does ADU construction typically cost?
Budget requirements differ 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 standalone backyard unit. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. A detailed estimate can only be produced following a full site assessment.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Standalone ADU projects are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you do not need to vacate your primary residence during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the process. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that briefly affect habitability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU can be expected to last as long as any standard residential structure — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds use commercial-grade materials 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 perfectly suited for ADU construction. Residents in the Rose Garden district have found their lots are well configured for ADU builds. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that experienced builders know well. 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 fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction for many different project types — from modest studio builds to fully independent secondary homes. Our approach opens with a comprehensive site assessment where we listen to your goals and share clear expectations of what the project will involve.
Reach out to our team to begin the conversation. Even if you're just exploring the idea, we're glad to answer questions, share examples of our work 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