Brother & Brother Builders

Unlock New Space with Professional ADU Construction

Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical 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 see these visions to life with skill and care.

The demand for ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. 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 requirements, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could mean for your property, this guide will walk you through 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 — including a kitchen, bathroom, sleeping area, and its own access point — that is located on the same parcel as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.

Mechanically, everything kicks off with a detailed site assessment, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the local building department. Once approvals are in place, ADU construction enters the physical build phase — which covers everything from foundational work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a move-in-ready living unit attached to or separate from your main home.

What sets quality ADU construction apart is the depth of planning at every stage. Materials must be selected to align with the neighborhood's character. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction contributes significant market value to your property, often increasing appraised value substantially 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, providing a consistent income stream for the homeowner.
• Multi-Generational Living — ADU construction offers family members a comfortable home of their own without leaving the property.
• Personalized Layouts — From modern studio layouts, ADU construction can be tailored to the intended occupant's lifestyle.
• Faster Permitting in California — 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.
• Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of requiring new development, 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 the long haul by offering both usable housing and equity growth.

The ADU Construction Process Step by Step

1. Site Evaluation and Zoning Analysis — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any resources go toward planning.
2. Architectural Drafting and Space Planning — Our design team create precise architectural drawings reflecting your priorities. Every square foot is planned to create practical, comfortable living.
3. 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.
4. Site Preparation and Foundation Work — Once permits are issued, physical construction begins. This includes grading the site, pouring the concrete foundation, and establishing utility connections.
5. Structural Framing and Weatherproofing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
6. Interior Systems and Infrastructure — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Inspections are completed at designated stages throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to the agreed design. A last official inspection grants legal occupancy status and the unit is officially approved for use.

Who Is a Right Fit for ADU Construction?

Homeowners who benefit most from ADU construction often belong to a few common profiles. If you own a single-family home with enough lot space to meet more info setback requirements, you're already well-positioned. 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 detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who want to maximize their land are also well suited for ADU construction, since the long-term value is proven.

Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may require additional review. Brother & Brother Builders reviews each property on its own merits to provide realistic options.

ADU Construction Frequently Asked Questions

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 local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while larger new construction ADUs require more time.

What does ADU construction typically cost?

Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, 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 difficult to live through while it's underway?

The day-to-day impact depends on the project's location on your property. New construction in the rear yard are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.

Do I need to move out during ADU construction?

In most cases, you are not required to vacate your house during ADU construction. The vast majority of projects are set up to let you continue living in the home throughout the process. Certain situations could require a brief departure if interior conversion work touches shared systems in ways that temporarily impact livability. Our project managers will flag these situations during the pre-construction consultation.

How long will an ADU built through professional ADU construction last?

A well-built ADU can be expected to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and build to current California residential standards to ensure lasting performance.

ADU Construction for Local Homeowners

Residential areas across San Jose present a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.

San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.

Schedule Your ADU Construction Assessment Today

Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU construction across a wide range of project types — from small attached additions to fully independent secondary homes. The process begins with a thorough and honest property review where we listen to your goals and share clear expectations of what's achievable.

Get in touch with our office to set up your consultation. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. ADU construction is a significant investment — and our goal is to ensure it delivers real value.

Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632