Transform Your Property with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with skill and integrity.
The demand for ADU construction has increased significantly 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 supported the trend as a way to increase density responsibly. Whether you want to build 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 bring years of hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the design choices 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 an ADU Build?
ADU construction describes 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 — including a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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 thorough property evaluation, 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 the paperwork is cleared, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready 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. 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 treats each project with the same professional rigor we use on major custom home projects.
Key Benefits 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 can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a self-contained residence without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the barriers and delays associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of expanding urban sprawl, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU holds its value for the long haul by offering both functional space and financial upside.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Experienced draftspeople 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 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 granted, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. During this step, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Every system is reviewed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. A closing municipal review confirms the unit is code-compliant 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 often belong to a few common profiles. If you are a homeowner 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.
You may also be someone who runs a small business and wants a separate office or studio space that is distinct from your family's daily life. Real estate-minded homeowners who want to maximize their land are also well suited 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. Parcels in historic districts or HOA-restricted communities may need a modified approach. Our experts will evaluate each property case by case to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The complete duration click here for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take several months in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on the project's location on your property. Standalone ADU projects are typically less disruptive, since the crew operates at a distance from your living areas. Projects that connect to the main structure may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
In most cases, you do not need to vacate your house during ADU construction. Most job sites are structured to allow you continue living in the home throughout the process. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
Any ADU built to code with professional oversight can be expected to last as long as your primary home — typically 50 years or more. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a diverse mix of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties work well for both attached and detached projects. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
The City of San Jose's building department has developed specific protocols for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can affect how quickly permits are approved for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.
Book Your ADU Construction Assessment Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer licensed expertise in ADU construction for many different project types — from small attached additions to fully independent secondary homes. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and share clear expectations of what's achievable.
Get in touch with our office to begin the conversation. Whether you're in the early stages of planning, we enjoy discuss timelines, costs, and design possibilities 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