Expand Your Home with Quality ADU Construction

Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with skill and integrity.

The interest in ADU construction has surged in recent years, and it's no mystery. California state law has simplified the process for homeowners to build these secondary units, and local municipalities like San Jose have encouraged 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 gives you more 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 is familiar with city and county requirements, the engineering requirements, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.

What Is the ADU Construction Process?

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 self-contained living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel 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, the work starts with a detailed site assessment, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site here preparation, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit attached to or separate from your main home.

What separates excellent ADU construction from an average project is the depth of planning 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 handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.

Key Advantages ADU Construction

• Boosted Home Equity — ADU construction contributes significant market value to your property, often increasing appraised value substantially when it's time to sell.
• Revenue Generation — A completed ADU may be listed as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
• Space for Loved Ones — ADU construction offers family members a self-contained residence without moving to another neighborhood.
• Personalized Layouts — From open-plan one-bedrooms, ADU construction is adaptable to your specific needs.
• Streamlined Approval Process — 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 maximizes the land you already own instead of expanding urban sprawl, which supports broader sustainability goals.
• Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
• Lasting Financial Benefit — A well-built ADU remains an asset for decades, providing both usable housing and equity growth.

The ADU Construction Journey Step by Step

1. Property Walkthrough and Feasibility Check — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any money is spent on design.
2. Blueprint Development and Layout Design — Our design team create detailed floor plans reflecting your priorities. Every square foot is planned 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 sign-off and verification. We manage this entire process on your behalf, resolving any revision requests promptly.
4. Site Preparation and Foundation Work — Once permits are issued, the build starts. This includes grading the site, laying the structural base, and setting up utilities.
5. Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. This phase, the ADU transforms from a concept to a building.
6. Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU operationally complete. Inspections are completed at required milestones throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to the agreed design. A closing municipal review confirms the unit is code-compliant and your new space is cleared 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 a backyard, garage, or basement that could be converted, you're already in a good starting place. 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.

Another strong candidate is someone who needs a dedicated professional workspace and wants a separate office or studio space that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since the return on investment is well-documented.

Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Brother & Brother Builders reviews each property case by case 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 typically ranges from six to fourteen months, based on the project scope and city review schedules. City review on its own can take several months in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.

What does ADU construction typically cost?

Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions are generally priced lower, sometimes in the $80,000 to $150,000 range. An accurate budget can only be produced following a formal feasibility evaluation.

Is ADU construction disruptive while it's underway?

The level of disruption depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions may require temporary access during certain phases of construction. Brother & Brother Builders keeps you informed about upcoming work and timelines.

Do I need to leave my home during ADU construction?

For the majority of homeowners, you do not need to vacate your main home during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the construction timeline. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. Our construction supervisors will walk you through any potential disruptions during the planning phase.

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

A well-built ADU should last as long as any standard residential structure — typically 50 years or more. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. We select high-quality components and follow all code requirements to deliver a structure that stands the test of time.

ADU Construction for Local Homeowners

Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood have found their lots accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team knows the permitting landscape well.

Local regulatory bodies in this area follows defined procedures for ADU construction that our team navigates routinely. Proximity to transit corridors 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.

Schedule Your ADU Construction Planning Session Today

If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction for many different project types — from modest studio builds to multi-room backyard residences. The process begins with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what the project will involve.

Get in touch with our office 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 help you take the next step. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.

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