Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding 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 guided hundreds of local homeowners bring these projects to life with craftsmanship and integrity.
The popularity of ADU construction has surged in recent years, and it's easy to understand 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 address housing needs. 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 requirements, and the aesthetic decisions that make an ADU functional. If you've been thinking about what ADU construction could do for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — equipped with 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 basement or interior conversions.
Mechanically, everything kicks off with a thorough property evaluation, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. 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 complement the existing structure. Systems like HVAC and drainage must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction contributes significant market value to your property, often increasing appraised value substantially 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, generating steady monthly revenue for the homeowner.
- Housing for Extended Family — ADU construction offers family members a self-contained residence without losing proximity to the family.
- Design Flexibility — From open-plan one-bedrooms, ADU construction can be tailored to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced 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 maximizes the land you already own instead of requiring new development, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Long-Term Investment Security — A well-built ADU holds its value for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what ADU types will work before any time is invested in drawings.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — 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, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are issued, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — Framing is completed followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are placed and inspected to your specifications. A final city inspection confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, 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.
You may also be someone who runs a small business and wants a private work environment that remains away from your family's daily life. Property investors and rental owners who want to maximize their land are also a natural fit for ADU construction, since rental income frequently offsets here build costs.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Sites with underground infrastructure conflicts may face additional constraints. Our team can assess each property case by case to advise you on what's feasible.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. City review on its own can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions may complete more quickly, while multi-room detached cottages require more time.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on whether it's a conversion or new construction. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects often come in under, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be produced following a thorough property review.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are typically less disruptive, since the construction zone is separate. Garage conversions or attached additions may create short-term inconveniences during specific stages like framing or MEP rough-in. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you do not need to vacate your main home during ADU construction. Most builds are set up to let you continue living in the home throughout the build. Exceptions may arise if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will discuss these scenarios during the kickoff meeting.
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 your primary home — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Our builds use 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
San Jose's neighborhoods offer a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols 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 smoother project delivery from design through the final walkthrough.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction including all types of project types — from small attached additions to multi-room backyard residences. Our approach opens with a detailed, no-pressure consultation where we understand your vision and share clear expectations of what's achievable.
Reach out to our team to schedule a site visit. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects and give you the clarity you need to move forward. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632