Transform Your Property with Professional ADU Construction
Property owners throughout 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 powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with skill and integrity.
The demand for ADU construction has surged in recent years, and it's no mystery. California state law now makes it easier for homeowners to construct 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 provides increased control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU functional. When you're ready to explore what ADU construction could do for 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 self-contained living space — including a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, everything kicks off with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit connected to or independent of your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same professional rigor we use on major custom home projects.
Key Benefits ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU is leasable 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 moving to another neighborhood.
- Design Flexibility — 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, resulting in a timeline 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 aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU continues to produce returns for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any money is spent on design.
- Architectural Drafting and Space Planning — Our design team create precise architectural drawings tailored to your needs. 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 sign-off and verification. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. This phase, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. All work is inspected at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A final city inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction typically fall into a few clear categories. If you have a residential property 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 common ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who runs a small business and wants a private work environment that doesn't interfere with your family's daily life. Real estate-minded homeowners who want to maximize their land are also well suited for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first 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 FAQ
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. Permitting alone can take two to four months in San Jose, so starting early is important. Smaller detached units often finish in the lower end of the range, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a detached new build. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a full site assessment.
Is ADU construction difficult to live through while it's underway?
The level of disruption depends on where the ADU is being built. Detached backyard builds are typically less disruptive, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. Our team communicates clearly about what to expect at each stage.
Do I need to move out during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. Most job sites are designed so that you stay in your primary unit throughout the build. There are edge cases if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our construction supervisors will walk you through any potential disruptions website 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 any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. We select residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are perfectly suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots are well configured for ADU builds. The Berryessa area have seen growing ADU activity as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey 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.
Book Your ADU Construction Consultation Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our experts offer licensed expertise in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. Every project starts with a detailed, no-pressure consultation where we understand your vision and give you a realistic picture of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, 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