Unlock New Space with Professional ADU Construction
Property owners throughout San Jose, CA are discovering 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 precision and integrity.
The interest in ADU construction has surged in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is an ADU Build?
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 fully independent living space — equipped with 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 detailed site assessment, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans 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, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit connected to or independent of your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same technical discipline we apply to large-scale 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, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Customization Options — From open-plan one-bedrooms, ADU construction may be customized to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of requiring new development, which supports broader 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 decades, providing both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints reflecting your priorities. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — 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, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This includes grading the site, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Inspections are completed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review grants legal occupancy status 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 common profiles. If you own a single-family home with enough lot space to meet setback requirements, 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 supporting elderly parents.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely 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 standalone backyard unit. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to leave my home during ADU construction?
Generally speaking, you do not need to vacate your main home during ADU construction. Most job sites are structured to allow you remain on the property throughout the construction timeline. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction last?
A well-built ADU can be expected to last as long as your primary home — often several decades with routine maintenance. Durability depends to the standard of construction, whether click here the unit is properly cared for, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and comply with all local building codes to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a wide range of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Consultation Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we understand your vision and provide an honest assessment of what's achievable.
Reach out to our team to begin the conversation. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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