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 rewarding investments they can make. ADU construction opens the door to a versatile 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 integrity.
The interest in ADU construction has surged 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're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property serves your household.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU beautiful. Should you want to learn about 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 engineering, filing for, and completing an accessory dwelling unit on a residential read more property. An accessory dwelling unit is a complete living space — including a kitchen, bathroom, sleeping area, and its own access point — 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 below-grade dwelling units.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we use on major 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.
- Monthly Cash Flow — A completed ADU can be rented 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 private, independent living space without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of requiring new development, 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 functional space and financial upside.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints based on your goals. 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 inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are issued, physical construction begins. This covers land preparation, laying the structural base, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to your specifications. A last official inspection confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few common profiles. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who want to maximize their land are also prime candidates for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property individually and honestly to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction usually 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. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units may complete more quickly, while custom detached builds take longer to complete.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the construction zone is separate. Interior conversions may require temporary access during key milestones. We provide advance notice about upcoming work and timelines.
Do I need to leave my home during ADU construction?
Generally speaking, you do not need to vacate your main home during ADU construction. Most builds are structured to allow you continue living in the home throughout the build. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and build to current California residential standards to protect your investment for the long haul.
ADU Construction for Local Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
San Jose's permitting office has developed specific protocols 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 the San Jose permitting environment means more accurate timelines and budgets from kickoff through certificate of occupancy.
Book Your ADU Construction Consultation Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction including all types of project types — from simple garage conversions to fully independent secondary homes. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Reach out to our team 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 make sure you feel confident before committing. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632