Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction opens the door to a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with precision and transparency.
The interest in ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting 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 offers greater control over how your property works.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could do for your property, this guide covers everything you need to know.
What Is an ADU Build?
ADU construction involves the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring a kitchen, bathroom, sleeping area, and its own entryway — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the local building department. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Products need to be chosen to align with the neighborhood's character. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
- Revenue Generation — A completed ADU is leasable 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 self-contained residence without losing proximity to the family.
- Customization Options — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the red tape associated with ADU construction, creating a path that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of requiring new development, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what's possible before any resources go toward planning.
- Blueprint Development and Layout Design — Our design team create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are issued, the build starts. This involves leveling and prepping the ground, completing foundation work, and setting up utilities.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A final city inspection grants legal occupancy status and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited from ADU construction generally fit within a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who needs a dedicated professional workspace and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited for ADU construction, since rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may need a modified approach. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and city review schedules. 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 can move faster, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on whether it's a conversion or new construction. 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 are generally priced lower, sometimes between $75,000 and $140,000. A detailed estimate can only be developed after a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
Generally speaking, you are not required to vacate your primary residence during ADU construction. Most builds are structured to allow you continue living in the home throughout the process. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our construction supervisors will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight is designed to last as long as the main residence — typically 50 years or more. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. We select commercial-grade materials and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a variety of property types that are well suited for ADU construction. Homeowners in the get more info Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
Local regulatory bodies in this area 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 the San Jose permitting environment means fewer surprises from the first meeting to the final inspection.
Start Your ADU Construction Consultation Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction for many different project types — from modest studio builds to multi-room backyard residences. Every project starts with a thorough and honest property review where we understand your vision and share clear expectations of what the project will involve.
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