Transform Your Property with Expert ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with skill and care.
The demand for ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to construct 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 provides increased control over how your property functions.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the design choices that make an ADU beautiful. When you're ready to explore what ADU construction could do for your property, this guide covers everything you need to check here know.
What Is the ADU Construction Process?
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 complete living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction can take several forms, 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 builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which includes foundation work, 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 depth of planning at every stage. Components should be specified to complement the existing structure. 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 Advantages ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a comfortable home of their own without moving to another neighborhood.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to your household's priorities.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any resources go toward planning.
- Custom Design and Architectural Planning — Licensed architects and designers create comprehensive blueprints based on your goals. Every square foot is planned to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. We manage this entire process on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are placed and inspected 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 often belong to a few common profiles. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners hoping to offset mortgage costs 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 private work environment that doesn't interfere with your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction typically ranges from six to fourteen months, depending on design complexity and local permitting timelines. Permitting alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be produced following a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Interior conversions may require temporary access during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
In most cases, you won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. The team at Brother & Brother Builders will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight is designed to last as long as your primary home — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies commercial-grade materials and comply with all local building codes to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area often discover their properties accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors 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 the first meeting to the final inspection.
Start Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our builders provide licensed expertise in ADU construction across a wide range of project types — from simple garage conversions to fully independent secondary homes. The process begins with a detailed, no-pressure consultation where we understand your vision and share clear expectations of what the project will involve.
Get in touch with our office to schedule a site visit. 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 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