Unlock New Space with Professional ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a flexible here new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with precision and care.
The demand for ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. Whether you want to build 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 considerations, and the design choices that make an ADU truly livable. Should you want to learn about what ADU construction could mean for your property, this guide will walk you through 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 fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the work starts with a detailed site assessment, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit attached to or separate from your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction offers family members a self-contained residence without losing proximity to the family.
- Design Flexibility — From two-bedroom configurations, ADU construction may be customized to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Efficient Use of Your Lot — 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 occupants have full privacy.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This stage clarifies exactly what's possible before any money is spent on design.
- Architectural Drafting and Space Planning — Our design team 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 involves filing drawings to the city's building department for review and approval. 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 covers land preparation, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. At this stage, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are fitted and completed to your specifications. A final city inspection confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction often belong to a few common profiles. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who works from home and wants a private work environment that is distinct from your family's daily life. Landlords and real estate investors who are building a portfolio are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. City review on its own can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $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 given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
The level of disruption 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 key milestones. Our team communicates clearly about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you do not need to vacate your house during ADU construction. Most builds are designed so that you stay in your primary unit 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. Our construction supervisors will walk you through any potential disruptions during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU is designed to last as long as your primary home — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Our builds use high-quality components and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
Local regulatory bodies in this area follows defined procedures 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 the San Jose permitting environment means smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Assessment Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation 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 begin the conversation. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632