Expand Your Home with Professional ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with craftsmanship and integrity.
The popularity of ADU construction has increased significantly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. Whether you're building 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 apply deep hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering considerations, 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 explains everything you need to know.
What Is ADU Construction?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — 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 below-grade dwelling units.
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, 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 covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Housing for Extended Family — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Design Flexibility — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU remains an asset for the long haul by offering both functional space and financial upside.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any time is invested in drawings.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints reflecting your priorities. Layouts are carefully considered to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This includes grading the site, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to your specifications. A final city inspection 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 clear categories. 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 accommodating adult children who need housing.
ADU construction also suits someone who needs a dedicated professional workspace and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who already own residential properties are also well suited for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually 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. Permitting alone can take two to four 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 typically cost?
Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a full site assessment.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on the project's location on your property. New construction in the rear yard are typically less disruptive, since work happens away from the main house. Interior conversions may require temporary access during certain phases of construction. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you are not required to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that temporarily impact livability. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU should last as long as your primary home — typically 50 years or more. Durability depends to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a variety of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots accommodate detached backyard units nicely. The Berryessa area are increasingly popular for ADU construction as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. Proximity to transit corridors can impact the design approach for a given ADU project. Our familiarity with these local conditions means smoother project delivery from the first meeting to the final inspection.
Start Your ADU Construction Planning Session Today
Should you be thinking about how 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 for many different project types — from modest studio builds to fully independent secondary homes. Every project starts with a detailed, no-pressure consultation where we learn what you're trying to accomplish and share clear expectations of click here what ADU construction on your property will look like.
Get in touch with our office to schedule a site visit. Whether you're in the early stages of planning, we enjoy answer questions, share examples of our work and help you take the next step. 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