Transform Your Property with Expert 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 powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners website turn these plans to life with precision and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. Whether you're building 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 understands the local permitting process, the engineering details, and the aesthetic decisions that make an ADU beautiful. When you're ready to explore what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of designing, permitting, and building 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 sits on the same property 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, the work starts with a comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Components should be specified 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 apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction contributes significant 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, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a private, independent living space without leaving the property.
- Customization Options — From modern studio layouts, ADU construction may be customized to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of consuming open land, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any money is spent on design.
- Architectural Drafting and Space Planning — Our design team create comprehensive blueprints based on your goals. Space is thoughtfully allocated 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, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are approved, the build starts. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — Framing is completed followed by insulation, sheathing, and exterior cladding. During this step, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. All work is inspected at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few clear categories. If you own a single-family home with available square footage under zoning rules, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who needs a dedicated professional workspace and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who want to maximize their land 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 need a modified approach. Our experts will evaluate each property on its own merits to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and local permitting timelines. Permitting alone can take a significant portion of the overall timeline 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 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. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget 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 where the ADU is being built. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
In most cases, you won't have to vacate your primary residence during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. We select commercial-grade materials and follow all code requirements 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. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. The Berryessa area have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team knows the permitting landscape well.
San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from the first meeting to the final inspection.
Start Your ADU Construction Assessment Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction for many different project types — from small attached additions to multi-room backyard residences. The process begins with a thorough and honest property review where we understand your vision and provide an honest assessment of what the project will involve.
Get in touch with our office to schedule a site visit. No matter where you are in the decision-making process, we enjoy answer questions, share examples of our work and give you the clarity you need to move forward. 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