Unlock New Space 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 provides a flexible new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with skill and integrity.
The popularity of ADU construction has grown rapidly in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the website housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property functions.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the aesthetic decisions that make an ADU beautiful. Should you want to learn about what ADU construction could do for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — equipped with 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 interior space reconfigurations.
Mechanically, the process begins with a comprehensive review of your lot, where our team 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 enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. 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. Products need to be chosen to align with the neighborhood's character. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often generating strong equity gains when it's time to sell.
- Monthly Cash Flow — A completed ADU may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream 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 your household's priorities.
- Streamlined Approval Process — Recent state legislation has reduced the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU remains an asset for many years and generates both usable housing and equity growth.
The ADU Construction Process Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what can be built before any time is invested in drawings.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints reflecting your priorities. Layouts are carefully considered to maximize function and livability.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. We manage this entire process on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This covers land preparation, completing foundation work, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. During this step, 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 ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are placed and inspected to your specifications. A last official inspection grants legal occupancy status and the ADU is ready 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 in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a private work environment that doesn't interfere with 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.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our team can assess each property individually and honestly to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, depending on design complexity and local permitting timelines. City review on its own can take two to four months in San Jose, so planning ahead matters. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Costs vary widely based on whether it's a conversion or new construction. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a full site assessment.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since the crew operates at a distance from your living areas. Garage conversions or attached additions may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to move out during ADU construction?
For the majority of homeowners, you won't have to vacate your main home during ADU construction. The vast majority of projects are set up to let you continue living in the home throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and if mechanical components are maintained on schedule. Our builds use high-quality components and follow all code requirements to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a variety of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
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 the first meeting to the final inspection.
Start Your ADU Construction Assessment Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is ready to guide you. Our experts offer proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a comprehensive site assessment where we understand your vision and provide an honest assessment of what's achievable.
Reach out to our team to set up your consultation. Even if you're just exploring the idea, we enjoy answer questions, share examples of our work and help you take the next step. 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