Brother & Brother Builders

Expand Your Home with Expert 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 generate rental income. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with craftsmanship and transparency.

The demand for ADU construction has surged in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have supported 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 gives you more control over how your property functions.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU functional. When you're ready to explore what ADU construction could do for your property, this guide will walk you through everything you need to know.

What Is the ADU Construction Process?

ADU construction involves 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 entryway — that sits on the same property as a primary residence. ADU construction can take several forms, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.

Mechanically, the work starts with a comprehensive review of your lot, where our builders 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 enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.

What separates excellent ADU construction from an average project is the attention to detail at every stage. Components should be specified to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we apply to large-scale custom home projects.

Key Benefits 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 can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
• Space for Loved Ones — ADU construction provides adult children a private, independent living space without losing proximity to the family.
• Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your specific needs.
• Faster Permitting in California — Recent state legislation has reduced the permitting obstacles associated with ADU construction, making the process that is faster and less expensive than ever before.
• Efficient Use of Your Lot — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
• Long-Term Investment Security — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Initial Property Assessment and Feasibility Review — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what ADU types will work before any time is invested in drawings.
2. Custom Design and Architectural Planning — Experienced draftspeople create detailed floor plans based on your goals. Space is thoughtfully allocated to maximize function and livability.
3. Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, responding to review feedback promptly.
4. Ground Prep and Structural Base — Once permits are approved, the build starts. This covers land preparation, completing foundation work, and running initial plumbing and electrical conduits.
5. Framing, Roofing, and Exterior Work — Framing is completed followed by roofing, siding, windows, and exterior doors. During this step, the ADU transforms from a concept to a building.
6. 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 each code checkpoint throughout ADU construction.
7. Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A last official inspection grants legal occupancy status and the ADU is ready for use.

Who Is a Right Fit for ADU Construction?

Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you own a single-family home with enough lot space to meet 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 navigating multigenerational living situations.

ADU construction also suits someone who needs a dedicated professional workspace and wants a separate office or studio space that is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since rental income frequently offsets build costs.

Those who should discuss alternatives first include lots that are below minimum size thresholds. Sites with underground infrastructure conflicts may need a modified approach. Our experts will evaluate 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 full timeline for ADU construction commonly spans six to fourteen months, influenced by the type of unit being built and city review schedules. The approval phase alone can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions often finish in the lower end of the range, while multi-room detached cottages fall toward the upper end of the timeline.

What does ADU construction typically cost?

Budget requirements differ based on project complexity and finishes more info selected. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.

Is ADU construction intrusive while it's underway?

The day-to-day impact depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Garage conversions or attached additions may require temporary access during key milestones. Brother & Brother Builders keeps you informed about any phases that may affect your routine.

Do I need to leave my home during ADU construction?

For the majority of homeowners, you are not required to vacate your primary residence during ADU construction. Most job sites are structured to allow you continue living in the home throughout the process. There are edge cases if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will flag these situations during the pre-construction consultation.

How long will an ADU built through professional ADU construction hold up?

An ADU constructed with quality materials is designed to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, whether the unit is properly cared for, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to protect your investment for the long haul.

ADU Construction for San Jose Homeowners

Residential areas across San Jose present a diverse mix of property types that are perfectly suited for ADU construction. Residents in the Rose Garden district often discover their properties are well configured for ADU builds. Communities around the Capitol Expressway corridor 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 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 this region's building landscape means more accurate timelines and budgets from kickoff through certificate of occupancy.

Book Your ADU Construction Assessment Today

When you want to add an ADU to your property, Brother & Brother Builders is here to help. We bring proven skills in ADU construction across a wide range of project types — from simple garage conversions to fully independent secondary homes. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.

Get in touch with our office to set up your consultation. Even if you're just exploring the idea, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. 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