Transform Your Property with Expert ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest 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 supported hundreds of local homeowners turn these plans to life with precision and integrity.
The interest in ADU construction has increased significantly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported 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 functions.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU functional. Should you want to learn about what ADU 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 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 interior space reconfigurations.
Mechanically, the work starts with a comprehensive review of your lot, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same technical discipline we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a private, independent living space without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
- Separate Entrances and Spaces — 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 the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any resources go toward planning.
- Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints based on your goals. Layouts are carefully considered to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. At this stage, the ADU takes its visible shape.
- MEP Systems Rough-In — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are installed and finished to the agreed design. A final city inspection issues the certificate of occupancy and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a detached creative or business space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also a natural fit for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our experts will evaluate each property on its own merits to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while multi-room detached cottages require more time.
What does ADU construction usually run in terms of budget?
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 fully custom construction. Interior conversion projects often come in under, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are typically less disruptive, since the construction zone is separate. Interior conversions may involve some shared wall work during key milestones. We provide advance notice about what to expect at each stage.
Do I need to move out during ADU construction?
For the majority of homeowners, you won't have to vacate your house during ADU construction. The vast majority of projects are designed so that you continue living in the home throughout the process. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that briefly affect habitability. The team at Brother & Brother Builders will walk you through any potential disruptions during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. How long it lasts comes down to the standard of construction, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. We select residential-grade products rated for longevity and build to current California residential standards to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
Local regulatory bodies in this area applies particular standards for ADU construction that require a builder read more 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 more accurate timelines and budgets 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 here to help. Our builders provide 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 learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. Building an ADU is a major decision — 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