Unlock New Space with Quality ADU Construction
Families in 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 powerful 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 skill and care.
The interest in ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you're building 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 bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU functional. Should you want to learn about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is an ADU Build?
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 complete living space — featuring a kitchen, bathroom, sleeping area, and its own entrance — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins 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 relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit connected to or independent of your main home.
What separates excellent ADU construction from an average project is the level of craftsmanship at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be built for long-term residential demand. 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 adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Monthly Cash Flow — 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 gives aging parents a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction is adaptable to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, making the process that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which contributes to sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU remains an asset for decades, providing both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints reflecting your priorities. Layouts are carefully considered to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for review and approval. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are granted, on-site work kicks off. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A closing municipal review confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few clear categories. If you are a homeowner with available square footage under zoning rules, you're already well-positioned. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who runs a small business and wants a private work environment that remains away from your family's daily life. Landlords and real estate investors who are building a portfolio are also well suited for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Brother & Brother Builders reviews each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, based on the project scope and city review schedules. Permitting alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units 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 whether it's a conversion get more info 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 often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection 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 the project's location on your property. New construction in the rear yard are generally the least intrusive, since the construction zone is separate. Garage conversions or attached additions may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to move out during ADU construction?
Generally speaking, you are not required to vacate your main home during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the construction timeline. Exceptions may arise if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios 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 can be expected to last as long as the main residence — typically 50 years or more. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies residential-grade products rated for longevity and comply with all local building codes to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
Residential areas across San Jose present a wide range of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district frequently see their parcels are well configured for ADU builds. 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.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. We bring proven skills in ADU construction for many different project types — from modest studio builds to large custom detached cottages. Our approach opens with a thorough and honest property review 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. Even if you're just exploring the idea, we enjoy 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