Unlock New Space with Expert ADU Construction
Homeowners across 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 versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with precision and integrity.
The popularity of ADU construction has increased significantly 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 supported the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering details, and the aesthetic decisions that make an ADU functional. If you've been thinking about what ADU construction could look like on your property, this guide covers 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 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 can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the work starts with a comprehensive review of your lot, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — 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.
- Housing for Extended Family — ADU construction gives aging parents a self-contained residence without leaving the property.
- Customization Options — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU continues to produce returns for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
- Permit Submission and Municipal Review — 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 approved, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by insulation, sheathing, and exterior cladding. This phase, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are placed and inspected to the approved plan. A last official inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few clear categories. If you are a homeowner with available square footage under zoning rules, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who works from home and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Our team can assess each property case by case to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally 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. Permitting alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions may complete more quickly, while multi-room detached cottages take longer to complete.
What does ADU construction cost in San Jose?
Pricing depends on many factors 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 detached new build. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. The vast majority of projects are designed so that you continue living in the home throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials can be expected to last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and how proactively issues get more info are resolved over time. Brother & Brother Builders specifies commercial-grade materials and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of the San Jose permitting environment means smoother project delivery from kickoff through certificate of occupancy.
Start 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 including all types of project types — from small attached additions to fully independent secondary homes. Every project starts with a thorough and honest property review 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 help you take the next step. ADU construction is a significant investment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632