Expand Your Home with Quality ADU Construction
Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a powerful 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 craftsmanship and care.
The popularity of ADU construction has surged in recent years, and it's no mystery. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have embraced 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 serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the design choices that make an ADU truly livable. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
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 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 basement or interior conversions.
Mechanically, the work starts with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, ADU construction moves into the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like HVAC and drainage must get more info be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we bring to full custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without leaving the property.
- Design Flexibility — From open-plan one-bedrooms, ADU construction may be customized to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for decades, providing both functional space and financial upside.
The ADU Construction Procedure 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 phase answers exactly what can be built before any resources go toward planning.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints tailored to your needs. Space is thoughtfully allocated to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are approved, the build starts. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
- Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. This phase, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to the approved plan. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you have a residential property with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
Another strong candidate is someone who needs a dedicated professional workspace and wants a detached creative or business space that doesn't interfere with 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.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our team can assess 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 full timeline 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 several months in San Jose, so starting early is important. Simpler garage conversions may complete more quickly, while larger new construction ADUs require more time.
What does ADU construction usually run in terms of budget?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may create short-term inconveniences during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. Most builds are structured to allow you remain on the property throughout the process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our project managers 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?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — indefinitely with proper upkeep. Durability depends to the systems installed, how well routine maintenance is performed, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Residents in the Rose Garden district have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
The City of San Jose's building department applies particular standards for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction across a wide range of project types — from modest studio builds to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we understand your vision and provide an honest assessment of what ADU construction on your property will look like.
Reach out to our team to begin the conversation. Whether you're in the early stages of planning, we're glad to discuss timelines, costs, and design possibilities and help you take the next step. 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