Unlock New Space with Expert ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a versatile 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 craftsmanship and care.
The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to address housing needs. 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 works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction describes the process of engineering, filing for, and completing 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 entrance — that is located on the same parcel 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, everything kicks off with a comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. 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 level of craftsmanship at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — 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 may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a comfortable home of their own without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction is adaptable to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU remains an asset for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. 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 comprehensive blueprints reflecting your priorities. Every square foot is planned to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This covers land preparation, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Licensed subcontractors 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.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are fitted and completed to your specifications. A last official inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few common profiles. If you have a residential property with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most motivated 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 remains away from your family's daily life. Property investors and rental owners who are building a portfolio 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 sites with unusual utility access challenges. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and city review schedules. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while multi-room detached cottages take longer to complete.
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 typically ranges from $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
How much the more info build affects daily life depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed 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 main home during ADU construction. Most job sites are structured to allow you stay in your primary unit throughout the build. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — typically 50 years or more. Durability depends to the quality of materials used, 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 follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has likely worked nearby.
Local regulatory bodies in this area follows defined procedures for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Planning Session Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction for many different project types — from small attached additions to large custom detached cottages. Our approach opens with a thorough and honest property review where we understand your vision and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to begin the conversation. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632