Transform Your Property with Quality ADU Construction
Families in San Jose, CA are finding 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 generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with craftsmanship and care.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier 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're building 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 apply deep hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the design choices that make an ADU functional. 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 an ADU Build?
ADU construction refers to the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring 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, everything kicks off with a comprehensive review of your lot, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Products need to be chosen to align with the neighborhood's character. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same professional rigor we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction may be customized to your household's priorities.
- Streamlined Approval Process — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of requiring new development, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for the long haul by offering both usable housing and equity growth.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what can be built before any resources go toward planning.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints tailored to your needs. Every square foot is planned to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are issued, the build starts. This covers land preparation, pouring the concrete foundation, and setting up utilities.
- Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are placed and inspected to your specifications. A closing municipal review confirms the unit is code-compliant 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 common profiles. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families supporting elderly parents.
You may also be someone who runs a small business and wants a detached creative or business space that remains away 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 return on investment is well-documented.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, based on the project scope and how quickly approvals come through. City review on its own can adu construction San Jose take several months in San Jose, so planning ahead matters. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Attached ADU additions often come in under, sometimes between $75,000 and $140,000. A detailed estimate can only be produced following a formal feasibility evaluation.
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. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Projects that connect to the main structure may require temporary access during specific stages like framing or MEP rough-in. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you won't have to vacate your main home during ADU construction. The vast majority of projects are structured to allow you stay in your primary unit throughout the construction timeline. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight can be expected to last as long as the main residence — typically 50 years or more. Durability depends to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. 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 variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as housing demand rises. Whether your property is near downtown San Jose, our team has likely worked nearby.
San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across these local conditions means smoother project delivery from kickoff through certificate of occupancy.
Book 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 builders provide licensed expertise in ADU construction across a wide range of project types — from small attached additions 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 share clear expectations of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we enjoy discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. ADU construction is a significant investment — 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