Brother & Brother Builders

Transform Your Property with Quality ADU Construction

Homeowners across San Jose, CA are realizing 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 create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners see these visions to life with precision and care.

The popularity of ADU construction has increased significantly in recent years, and it's no mystery. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property functions.

At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the planning steps 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 an ADU Build?

ADU construction refers to the process of engineering, filing for, and completing 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 access point — that exists on the same lot 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 process begins with a thorough property evaluation, where our professionals evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the relevant municipal authority. Once permits are secured, 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 connected to or independent of your main home.

What separates excellent ADU construction from an average project is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders handles every ADU construction job with the same technical discipline we use on major custom home projects.

Key Reasons to Choose 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 can be rented as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Space for Loved Ones — ADU construction offers family members a comfortable home of their own without leaving the property.
• Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
• Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Sustainable Land Use — Building an ADU maximizes the land you already own instead of consuming open land, which contributes to sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
• Lasting Financial Benefit — A well-built ADU remains an asset for decades, providing both livable square footage and monetary benefit.

The ADU Construction Journey Step by Step

1. Property Walkthrough and Feasibility Check — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This stage clarifies exactly what's possible before any money is spent on design.
2. Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings reflecting your priorities. Space is thoughtfully allocated 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 sign-off and verification. Our team handles all submissions on your behalf, addressing any city comments promptly.
4. Ground Prep and Structural Base — Once permits are issued, the build starts. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
5. Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
6. MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A final city inspection issues the certificate of occupancy and the ADU is ready for use.

Who Is a Good Candidate for ADU Construction?

People who see the greatest return from ADU construction generally fit within a few common profiles. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.

You may also be 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 are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.

Those who should discuss alternatives first include lots that are below minimum size thresholds. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our experts will evaluate each property individually and honestly to advise you on what's feasible.

ADU Construction FAQ

How long does ADU construction typically take from start to finish?

The total process for ADU construction typically ranges from six to fourteen months, based on the project scope and city review schedules. Permitting alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Smaller detached units can move faster, while custom detached builds require more time.

What does ADU construction typically cost?

Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be produced following a full site assessment.

Is ADU construction disruptive while it's underway?

The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since the crew operates at a distance from your living areas. Interior conversions may create short-term inconveniences during certain phases of construction. Our team communicates clearly about what to expect at each stage.

Do I need to vacate the property during ADU construction?

In most cases, you won't have to vacate your main home during ADU construction. Most job sites are structured to allow you continue living in the home throughout the construction timeline. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. Our construction supervisors will flag these situations during the kickoff meeting.

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

An ADU constructed with quality materials should last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the systems installed, whether the unit here is properly cared for, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and comply with all local building codes to deliver a structure that stands the test of time.

ADU Construction for San Jose Homeowners

San Jose's neighborhoods offer a diverse mix of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team has project experience in the area.

San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.

Schedule Your ADU Construction Assessment Today

When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a thorough and honest property review where we understand your vision and provide an honest assessment of what's achievable.

Reach out to our team to set up your consultation. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work and give you the clarity you need to move forward. ADU construction is a significant investment — and we want to make sure it's the right one for you.

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