Unlock New Space with Quality 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 provides a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with craftsmanship and integrity.
The popularity of ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged 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 offers greater control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU beautiful. If you've been thinking about what ADU construction could do for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction describes 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 — including 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 interior space reconfigurations.
Mechanically, everything kicks off with a detailed site assessment, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction transitions to 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. Materials must be selected to align with the neighborhood's character. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — 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 may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Multi-Generational Living — ADU construction provides adult children a private, independent living space without losing proximity to the family.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU remains an asset for the long haul by offering both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what ADU types will work before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Layouts are carefully considered 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 sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, physical construction begins. 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 takes its visible shape.
- Interior Systems and Infrastructure — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. All work is inspected at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A final city inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you have a residential property with enough lot space to meet setback requirements, you're already well-positioned. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who runs a small business and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who already own residential properties are also a natural fit for here ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate 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 advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions may complete more quickly, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a thorough property review.
Is ADU construction disruptive while it's underway?
The level of disruption depends on where the ADU is being built. New construction in the rear yard are usually easier to live alongside, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you do not need to vacate your primary residence during ADU construction. Most job sites are set up to let 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 walk you through any potential disruptions during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as the main residence — typically 50 years or more. How long it lasts comes down to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. We select commercial-grade materials 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 ideally positioned for ADU construction. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. The Berryessa area are seeing more homeowners add secondary units as families expand. 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 applies particular standards for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our team's knowledge of the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.
Book Your ADU Construction Assessment Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. We bring licensed expertise in ADU construction for many different project types — from small attached additions to large custom detached cottages. 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.
Contact Brother & Brother Builders to schedule a site visit. Even if you're just exploring the idea, our team is happy to walk through your options, review completed projects and make sure you feel confident before committing. 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