Brother & Brother Builders

Expand Your Home with Expert ADU Construction

Families in 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 supported hundreds of local homeowners bring these projects to life with precision and transparency.

The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have encouraged the trend as a way to address housing needs. If you're planning 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 project. Our team knows the San Jose building codes, the engineering details, and the planning steps that make an ADU functional. Should you want to learn about 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 refers to 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 — equipped with a kitchen, bathroom, sleeping area, and its own entryway — 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 basement or interior conversions.

Mechanically, the work starts with a detailed site assessment, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction moves into the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a move-in-ready living unit adjacent to or detached from your main home.

The difference between a good and a great ADU build is the level of craftsmanship at every stage. Products need to be chosen to align with the neighborhood's character. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same high standards we bring to full custom home projects.

Key Advantages ADU Construction

• Higher Resale Potential — ADU construction contributes significant market value to your property, often generating strong equity gains when it's time to sell.
• Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Space for Loved Ones — ADU construction provides adult children a self-contained residence without moving to another neighborhood.
• Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
• Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
• Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
• Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
• Long-Term Investment Security — A well-built ADU holds its value for decades, providing both functional space and financial upside.

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 can be built before any money is spent on design.
2. Custom Design and Architectural Planning — Our design team create comprehensive blueprints based on your goals. Layouts are carefully considered to create practical, comfortable living.
3. Filing for Building Permits — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
4. Site Preparation and Foundation Work — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, completing foundation work, and establishing utility connections.
5. Structural Framing and Weatherproofing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
6. Interior Systems and Infrastructure — Skilled tradespeople install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. All work is inspected at required milestones throughout ADU construction.
7. Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are fitted and completed to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.

Who Is a Right Fit for ADU Construction?

People who see the greatest return from ADU construction typically fall into a few clear categories. If you have a residential property with a backyard, garage, or basement that could be converted, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.

You may also be someone who works from home and wants a private work environment that is distinct from your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.

Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may require additional review. Our experts will evaluate each property case by case to provide realistic options.

ADU Construction FAQ

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

The total process for ADU construction typically ranges from six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take two to four months in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while custom detached builds take longer to complete.

What does ADU construction usually run in terms of budget?

Costs vary widely based on whether it's a conversion or new construction. Locally, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. A precise cost projection can only be developed after 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 generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about what to expect at each stage.

Do I need to leave my home during ADU construction?

In most cases, you do not need to vacate your house during ADU construction. Most builds are set up to let you remain on the property throughout the construction timeline. There are edge cases if major utility upgrades affect the main house 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 remain in good condition?

Any ADU built to code with professional oversight can be expected to last as long as your primary home — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how well routine maintenance is performed, and how proactively issues are resolved over time. We select high-quality components and build to current California residential standards to ensure lasting performance.

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 often discover their properties are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has project experience in read more the area.

The City of San Jose's building department applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of the San Jose permitting environment means more accurate timelines and budgets from design through the final walkthrough.

Schedule Your ADU Construction Consultation Today

When you want to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. The process begins with a comprehensive site assessment where we listen to your goals and share clear expectations of what ADU construction on your property will look like.

Contact Brother & Brother Builders to schedule a site visit. Even if you're just exploring the idea, we enjoy discuss timelines, costs, and design possibilities and help you take the next step. 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