Transform Your Property with Professional ADU Construction
Homeowners across San Jose, CA are realizing 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 generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with precision and care.
The popularity of ADU construction has surged in recent years, and it's easy to understand why. 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 expand the housing supply. If you're planning 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 job. Our team is familiar with city and county requirements, the engineering requirements, and the design choices that make an ADU functional. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to 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 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 interior space reconfigurations.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once approvals are in place, ADU construction enters the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit attached to or separate 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 match the primary home's aesthetic. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction provides adult children a private, independent living space without leaving the property.
- Design Flexibility — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU holds its value for decades, providing both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any resources go toward planning.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans tailored to your needs. 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 inspection and clearance. We manage this entire process on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. During this step, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few clear categories. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who works from home and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Brother & Brother Builders reviews 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 complete duration for ADU construction commonly spans six to fourteen months, based on the project scope and how quickly approvals come through. The approval phase alone can take several months in San Jose, so starting early is important. Smaller detached units can move faster, while multi-room detached cottages require more time.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be given after completing a full site assessment.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on the project's location on your property. Standalone ADU projects are typically less disruptive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
For the majority of homeowners, you are not required to vacate your primary residence during ADU construction. Most builds are set up to let you continue living in the home throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied 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 build to current California residential standards to ensure lasting performance.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
San Jose's permitting office 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. Brother & Brother Builders' experience across this region's building landscape means smoother project delivery from the first meeting to the final inspection.
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. 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 detailed, no-pressure consultation where we understand your vision and share clear expectations of what ADU construction on your property will look like.
Reach out to our team to begin the conversation. No matter where you are in the decision-making process, our team is happy to answer questions, share examples of our work and give you the Brother & Brother Builders adu construction 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