Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with craftsmanship 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 streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to increase density responsibly. Whether you're building 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 draw on extensive hands-on experience to every ADU construction job. Our team understands the local permitting process, the engineering considerations, and the planning steps that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to 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 entrance — that exists on the same lot as a primary residence. ADU construction can take several forms, 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 lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, 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 connected to or independent of your main home.
What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to align with the neighborhood's character. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we bring to full custom home projects.
Key Advantages 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.
- Space for Loved Ones — ADU construction offers family members a private, independent living space without losing proximity to the family.
- Customization Options — From modern studio layouts, ADU construction may be customized to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, making the process that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings reflecting your priorities. Every square foot is planned to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. This phase, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A final city inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few common profiles. If you are a homeowner with enough lot space to meet setback requirements, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors who want to maximize their land are also well suited for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our experts will evaluate each property individually and honestly to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Budget requirements differ 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 standalone backyard unit. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be produced following a full site assessment.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the construction zone is separate. Garage conversions or attached additions may require temporary access during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that briefly affect habitability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU is designed to last as long as any standard residential structure — typically 50 years or more. Durability depends to the systems installed, 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 San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are ideally positioned for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. 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 has likely worked nearby.
The City of San Jose's here building department follows defined procedures for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.
Get in touch with our office to schedule a site visit. No matter where you are in the decision-making process, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. This type of project is a meaningful commitment — 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