Transform Your Property with Professional ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates 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 turn these plans to life with craftsmanship and care.
The demand for 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 encouraged the trend as a way to expand the housing here supply. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU truly livable. When you're ready to explore what ADU construction could mean for your property, this guide covers everything you need to know.
What Is an ADU Build?
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 complete living space — including a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, everything kicks off with a thorough property evaluation, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional 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. Components should be specified to align with the neighborhood's character. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor we use on major custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction delivers real 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.
- Multi-Generational Living — ADU construction gives aging parents a self-contained residence without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the barriers and delays associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Long-Term Investment Security — A well-built ADU continues to produce returns for decades, providing both usable housing and equity growth.
The ADU Construction Journey 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 step tells you exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Licensed architects and designers create detailed floor plans reflecting your priorities. Space is thoughtfully allocated to create practical, comfortable living.
- Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This covers land preparation, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — 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.
- MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are installed and finished to your specifications. A last official inspection issues the certificate of occupancy 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 have a residential property with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners looking to generate income through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
ADU construction also suits 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 a natural fit for ADU construction, since the long-term value is proven.
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. Our experts will evaluate each property on its own merits to recommend the right path forward.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take several months in San Jose, so starting early is important. 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?
Budget requirements differ based on whether it's a conversion or new construction. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions are generally priced lower, sometimes between $75,000 and $140,000. A precise cost projection can only be produced following a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you won't have to vacate your main home during ADU construction. Most builds are set up to let you stay in your primary unit throughout the build. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. Our project managers will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as your primary home — often several decades with routine maintenance. How long it lasts comes down to the systems installed, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies residential-grade products rated for longevity and build to current California residential standards to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor 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.
The City of San Jose's building department follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our familiarity with the San Jose permitting environment means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Consultation Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction across a wide range of project types — from simple garage conversions to large custom detached cottages. Every project starts with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what the project will involve.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and make sure you feel confident before committing. 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