Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with precision and integrity.
The popularity of ADU construction has surged in recent years, and it's not hard to see 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 expand the housing supply. 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 draw on extensive hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU functional. When you're ready to explore what ADU construction could do for your property, this guide covers 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 — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, 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, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we bring to full custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of requiring new development, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU remains an asset for the long haul by offering both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Every square foot is planned to optimize daily use.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This includes grading the site, completing foundation work, and establishing utility connections.
- Shell Construction and Exterior Finishing — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you own a single-family home with available square footage under zoning rules, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a detached creative or business space that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Our experts will evaluate each property individually and honestly to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction commonly spans 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. Simpler garage conversions may complete more quickly, while custom detached builds take longer to complete.
What does ADU construction usually run in terms of budget?
Pricing depends on many factors based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions are generally priced lower, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be produced following a full site assessment.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
For the majority of homeowners, you won't have to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you stay in your primary unit throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that briefly affect habitability. The team more info at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
A well-built ADU should last as long as your primary home — often several decades with routine maintenance. Durability depends to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies high-quality components 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 diverse mix of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road 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 design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction including all types of project types — from modest studio builds to multi-room backyard residences. The process begins with a thorough and honest property review where we listen to your goals and share clear expectations of what's achievable.
Get in touch with our office to set up your consultation. No matter where you are in the decision-making process, we're glad to answer questions, share examples of our work and make sure you feel confident before committing. 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