Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with skill and transparency.
The demand for ADU construction has grown rapidly in recent years, and it's no mystery. 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 want to build 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 draw on extensive hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering requirements, and the design choices that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide covers 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 property. An accessory dwelling unit is a fully independent living space — including a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, everything kicks off 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 city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to align with the neighborhood's character. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — 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 self-contained residence without moving to another neighborhood.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and less expensive 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.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both usable housing and equity growth.
The ADU Construction Procedure 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 time is invested in drawings.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are issued, the build starts. This involves leveling and prepping the ground, laying the structural base, and setting up utilities.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. 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?
People who see the greatest return from ADU construction often belong to a few common profiles. If you own a single-family home with enough lot space to meet setback requirements, you're already well-positioned. Homeowners looking to generate income through rental are among the most common 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 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.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may require additional review. Our team can assess each property case by case to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, depending on design complexity and local permitting timelines. Permitting alone can take several months in San Jose, so starting early is important. Simpler garage conversions often finish in the lower end of the range, while larger new construction ADUs require more time.
What does ADU construction cost in San Jose?
Costs vary widely based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on the project's location on your property. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. Garage conversions or attached additions may involve some shared wall work during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. Most builds are designed so that you remain on the property throughout the process. There are edge cases if interior conversion work touches shared systems in ways that require short-term access disruption. Our project managers 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 should last as long as your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use commercial-grade materials and comply with all local building codes to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a diverse mix 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 have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
Local regulatory bodies in this area applies particular standards for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across these local conditions means fewer surprises from design through the final walkthrough.
Start Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer years of hands-on experience in ADU construction including all types of project types — from small attached additions to Brother & Brother Builders adu construction large custom detached cottages. 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 set up your consultation. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and help you take the next step. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632