Unlock New Space with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and integrity.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. If you're planning 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 job. Our team is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU beautiful. If you've been thinking 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 describes the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — equipped with a kitchen, bathroom, sleeping area, and its own access point — 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 interior space reconfigurations.
Mechanically, the work starts with a thorough property evaluation, where our professionals evaluate lot dimensions, existing structures, soil here conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which covers everything from foundational work, 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 level of craftsmanship at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same technical discipline we use on major custom home projects.
Key Advantages ADU Construction
- Boosted Home Equity — ADU construction delivers real 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, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU continues to produce returns for the long haul by offering both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any money is spent on design.
- Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings based on your goals. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — 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.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. All work is inspected at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A last official inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few common profiles. 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 common ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a detached creative or business space that remains away from your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Sites with underground infrastructure conflicts may require additional review. Our experts will evaluate each property case by case to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so starting early is important. Simpler garage conversions often finish in the lower end of the range, while custom detached builds take longer to complete.
What does ADU construction usually run in terms of budget?
Costs vary widely based on the type and size of the ADU. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. Detached backyard builds are usually easier to live alongside, since work happens away from the main house. Interior conversions may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
In most cases, you won't have to vacate your house during ADU construction. Most builds are designed so that you remain on the property throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as your primary home — often several decades with routine maintenance. Durability depends 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 comply with all local building codes to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that experienced builders know well. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our team's knowledge of the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.
Schedule Your ADU Construction Planning Session Today
When you want to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction including all types of project types — from small attached additions to large custom detached cottages. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what's achievable.
Get in touch with our office to set up your consultation. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and give you the clarity you need to move forward. Building an ADU is a major decision — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632