Expand Your Home with Expert ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with craftsmanship and transparency.
The interest in ADU construction has increased significantly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have embraced 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 works.
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 truly livable. Should you want to learn about what ADU construction could look like on your property, this guide will walk you through 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 entryway — that exists on the same lot 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 detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit connected to or independent of 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 plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction offers family members a comfortable home of their own without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of consuming open land, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Durable Return on Investment — A well-built ADU holds its value for the long haul by offering both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any money is spent on design.
- Blueprint Development and Layout Design — Our design team create precise architectural drawings based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. All work is inspected at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few common profiles. If you own a single-family home 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 motivated ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Landlords and real estate investors who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step 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 on its own merits to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction usually 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 city review schedules. The approval phase alone can take several months in San Jose, so starting early is important. Smaller detached units often finish in the lower end of the range, website while larger new construction ADUs take longer to complete.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on whether it's a conversion or new construction. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. A precise cost projection can only be developed after a full site assessment.
Is ADU construction disruptive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about upcoming work and timelines.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you are not required to vacate your main home during ADU construction. Most job sites are designed so that you continue living in the home throughout the process. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. Durability depends to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies residential-grade products rated for longevity 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 ideally positioned for ADU construction. Residents in the Rose Garden district have found their lots work well for both attached and detached projects. Communities around the Capitol Expressway corridor have seen growing ADU activity as families expand. 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 our team navigates routinely. Proximity to transit corridors can impact the design approach for a given ADU project. Brother & Brother Builders' experience across these local conditions means smoother project delivery from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. We bring licensed expertise in ADU construction including all types of project types — from small attached additions to fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation where we learn what you're trying to accomplish and give you a realistic picture of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. Whether you're in the early stages of planning, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. Building an ADU is a major decision — 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