Transform Your Property with Professional ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical 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 see these visions to life with craftsmanship and integrity.
The popularity of ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached here addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering details, and the planning steps that make an ADU functional. When you're ready to explore what ADU construction could look like on your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction refers to the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — including a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, everything kicks off with a thorough property evaluation, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once approvals are in place, ADU construction moves into the physical build phase — which includes foundation work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without losing proximity to the family.
- Personalized Layouts — 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.
- Responsible Property Development — Building an ADU uses your existing lot instead of expanding urban sprawl, which supports broader 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 functional space and financial upside.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any resources go toward planning.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Every square foot is planned to optimize daily use.
- Permitting and City Approval — 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, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are approved, the build starts. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few common profiles. If you own a single-family home with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
ADU construction also suits someone who runs a small business and wants a detached creative or business space that is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since rental income frequently offsets build costs.
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 FAQ
How long does ADU construction generally 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. Smaller detached units can move faster, while larger new construction ADUs fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely based on project complexity and finishes selected. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A detailed estimate can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on the project's location on your property. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. Interior conversions may require temporary access 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 move out during ADU construction?
For the majority of homeowners, you won't have to vacate your house during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the process. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our construction supervisors will flag these situations 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 can be expected to last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. We select commercial-grade materials and build to current California residential standards to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a variety of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Start Your ADU Construction Assessment Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer years of hands-on experience in ADU construction for many different project types — from modest studio builds to large custom detached cottages. The process begins with a thorough and honest property review where we listen to your goals and share clear expectations of what ADU construction on your property will look like.
Contact Brother & Brother Builders to begin the conversation. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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