Transform Your Property with Quality ADU Construction
Property owners throughout San Jose, CA are realizing 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 create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
The interest in ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have embraced 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 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 build. Our team knows the San Jose building codes, the engineering requirements, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could look like on your property, this guide will walk you through 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 comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins with a comprehensive review of your lot, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction transitions to 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.
The difference between a good and a great ADU build is the depth of planning at every stage. Components should be specified to align with the neighborhood's character. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Increased Property Value — 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, generating steady monthly revenue for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
- Design Flexibility — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which aligns with sustainability goals.
- Separate Entrances and Spaces — 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 remains an asset for decades, providing both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what's possible before any resources go toward planning.
- Architectural Drafting and Space Planning — Experienced draftspeople create detailed floor plans based on your goals. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are approved, the build starts. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A closing municipal review issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. 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 supporting elderly parents.
Another strong candidate is someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who want to maximize their land 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. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our team can assess each property on its own merits to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take several months in San Jose, so planning ahead matters. Straightforward interior conversions often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on whether it's a conversion or new construction. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost check here projection can only be produced following a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on the project's location on your property. New construction in the rear yard are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home during ADU construction?
In most cases, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you stay in your primary unit throughout the process. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight should last as long as any standard residential structure — typically 50 years or more. How long it lasts comes down to the standard of construction, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Our builds use commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots are well configured for ADU builds. Neighborhoods near Blossom Hill Road have seen growing ADU activity as families expand. Whether your property is near downtown San Jose, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Planning Session Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. We bring years of hands-on experience in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture of what the project will involve.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, we enjoy answer questions, share copyrightples of our work and help you take the next step. 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