Unlock New Space with Professional ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and transparency.
The popularity of 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 offers greater control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU functional. When you're ready to explore what ADU construction could mean for your property, this guide covers everything you need to know.
What Is ADU Construction?
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 — featuring a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the work starts with a thorough property evaluation, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which includes foundation 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. Materials must be selected to match the primary home's aesthetic. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often increasing appraised value substantially 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 provides adult children a private, independent living space without losing proximity to the family.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and less expensive than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of consuming open land, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU remains an asset for the long haul by offering both functional space and financial upside.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans based on your goals. Every square foot is planned to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. We manage this entire process on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are approved, the build starts. This includes grading the site, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are placed and inspected to the approved plan. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who needs a dedicated professional workspace and wants a detached creative or business space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Brother & Brother Builders reviews each property case by case to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction typically 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 city review schedules. The approval phase alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions often finish in the lower end of the range, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A precise cost projection can only be developed after a thorough property review.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during key milestones. We provide advance notice check here about any phases that may affect your routine.
Do I need to move out during ADU construction?
In most cases, you are not required to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you stay in your primary unit throughout the build. Exceptions may arise 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 planning phase.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials should last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. We select commercial-grade materials and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a wide range of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road are seeing more homeowners add secondary units as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Book Your ADU Construction Planning Session 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. We bring years of hands-on experience in ADU construction across a wide range of project types — from small attached additions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we understand your vision and provide an honest assessment of what the project will involve.
Contact Brother & Brother Builders to set up your consultation. Even if you're just exploring the idea, 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 our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632