Expand Your Home with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates 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 precision and transparency.
The demand for ADU construction has surged in recent years, and it's not hard to see why. 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 address housing needs. 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 apply deep hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — featuring 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 basement or interior conversions.
Mechanically, the process begins with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same technical discipline we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially 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 gives aging parents a self-contained residence without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction may be customized to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has cut down the barriers and delays associated with ADU construction, resulting in a timeline 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.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU remains an asset for many years and generates 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 stage clarifies exactly what can be built before any resources go toward planning.
- Architectural Drafting and Space Planning — Licensed architects and designers create comprehensive blueprints based on your goals. Space is thoughtfully allocated to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are issued, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
- Framing, Roofing, and Exterior Work — Framing is completed followed by weatherproofing and exterior finish materials. This phase, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are installed and finished to the agreed design. A last official inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few recognizable groups. If you have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who needs Brother & Brother Builders adu construction a dedicated professional workspace and wants a separate office or studio space that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also prime candidates 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. Sites with underground infrastructure conflicts may face additional constraints. Brother & Brother Builders reviews each property individually and honestly to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while multi-room detached cottages require more time.
What does ADU construction cost in San Jose?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a thorough property review.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Interior conversions may involve some shared wall work during certain phases of construction. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
For the majority of homeowners, you won't have to vacate your house during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the build. There are edge cases if major utility upgrades affect the main house in ways that briefly affect habitability. Our construction supervisors will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as the main residence — indefinitely with proper upkeep. Durability depends to the systems installed, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Our builds use residential-grade products rated for longevity and comply with all local building codes 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. Property owners near the Almaden Valley area have found their lots work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as housing demand rises. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area has developed specific protocols for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can impact the design approach for a given ADU project. Our team's knowledge of these local conditions means smoother project delivery from design through the final walkthrough.
Start Your ADU Construction Planning Session Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. Our experts offer proven skills in ADU construction for many different project types — from small attached additions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what the project will involve.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, we're glad to 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632