Transform Your Property with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with skill and integrity.
The demand for 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 supported the trend as a way to increase density responsibly. 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 apply deep hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering requirements, 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 covers everything you need to know.
What Is an ADU Build?
ADU construction describes 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 — featuring a kitchen, bathroom, sleeping area, and its own entrance — 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 below-grade dwelling units.
Mechanically, the process begins with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit attached to or separate from your main home.
The difference between a good and a great ADU build 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 sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Rental Income Potential — A completed ADU may be listed 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 private, independent living space without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has minimized the permitting obstacles associated with ADU construction, creating a path that is faster and less expensive 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 produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any money is spent on design.
- Architectural Drafting and Space Planning — Experienced draftspeople create detailed floor plans tailored to your needs. Every square foot is planned to maximize function and livability.
- 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.
- Ground Prep and Structural Base — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — The structural frame is erected 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 operationally complete. All work is inspected at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are installed and finished to the agreed design. A final city inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven 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 is distinct from your family's daily life. Landlords and real estate investors who already own residential properties are also prime candidates for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step 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 case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. Permitting alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on project complexity and finishes selected. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions are generally priced lower, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be developed after a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Garage conversions or attached additions may require temporary access during key milestones. We provide advance notice about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you do not need to vacate your house during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the process. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that temporarily impact livability. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials is designed to last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies commercial-grade materials and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are seeing more homeowners add secondary units as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in the area.
Local regulatory bodies in this area 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 affect how quickly permits are approved for a given ADU project. Our familiarity with these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
When you want 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 across a wide range of project types — from website simple garage conversions to large custom detached cottages. The process begins with a comprehensive site assessment where we listen to your goals and provide an honest assessment of what's achievable.
Get in touch with our office to set up your consultation. Even if you're just exploring the idea, we're glad to answer questions, share examples of our work and help you take the next step. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632