Expand Your Home with Quality ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with craftsmanship and transparency.
The popularity of ADU construction has increased significantly in recent years, and it's not hard to see why. 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 expand the housing supply. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU functional. When you're ready to explore what ADU construction could look like on your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction refers to the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own access point — 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, everything kicks off with a detailed site assessment, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction enters the physical build phase — which includes foundation 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.
What sets quality ADU construction apart is the depth of planning 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
- Higher Resale Potential — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU may be listed 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 comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has cut down the permitting obstacles associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Sustainable Land Use — 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 delivers a genuinely independent unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU remains an asset for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This phase answers 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 create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation 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 approved, physical construction begins. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by weatherproofing and exterior finish materials. During this step, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A final city inspection grants legal occupancy status 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 typically fall into a few clear categories. If you have a residential property with available square footage under zoning rules, 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 supporting elderly parents.
You may also be someone who needs a dedicated professional workspace and wants a private work environment that doesn't interfere with your family's daily life. Landlords and real estate investors who want to maximize their land are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Our experts will evaluate each more info property case by case to provide realistic options.
ADU Construction Frequently Asked Questions
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 how quickly approvals come through. Permitting alone can take two to four months in San Jose, so starting early is important. Straightforward interior conversions often finish in the lower end of the range, while custom detached builds require more time.
What does ADU construction typically cost?
Pricing depends on many factors 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. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be produced following a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on the project's location on your property. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
In most cases, you are not required to vacate your house during ADU construction. Most job sites are set up to let you continue living in the home throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight can be expected to last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the systems installed, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use high-quality components 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. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. The Berryessa area have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
Local regulatory bodies in this area has developed specific protocols 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. Our team's knowledge of this region's building landscape means smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Assessment Today
When you want to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide 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 detailed, no-pressure consultation where we learn what you're trying to accomplish and share clear expectations of what ADU construction on your property will look like.
Contact Brother & Brother Builders to begin the conversation. Even if you're just exploring the idea, we're glad to answer questions, share examples of our work and help you take the next step. ADU construction is a significant investment — 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