Expert ADU Construction Services for Homeowners

Unlock New Space with Expert ADU Construction

Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners turn these plans to life with precision and integrity.

The interest in ADU construction has grown rapidly in recent years, and it's no mystery. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have supported 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 provides increased control over how your property functions.

At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU beautiful. When you're ready to explore 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 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 entrance — 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 interior space reconfigurations.

Mechanically, the work starts with a thorough property evaluation, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a fully functional living unit adjacent to or detached from your main home.

What sets quality ADU construction apart is the depth of planning at every stage. Products need to be chosen to complement the existing structure. 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 high standards we use on major custom home projects.

Key Benefits ADU Construction

• Increased Property Value — ADU construction contributes significant market value to your property, often returning more than the build cost when it's time to sell.
• Rental Income Potential — A completed ADU is leasable as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
• Housing for Extended Family — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
• Customization Options — From two-bedroom configurations, ADU construction can be tailored to your household's priorities.
• Faster Permitting in California — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
• Responsible Property Development — Building an ADU works within your current footprint 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 residents have their own space.
• Long-Term Investment Security — 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. Initial Property Assessment and Feasibility Review — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what ADU types will work before any resources go toward planning.
2. Custom Design and Architectural Planning — Experienced draftspeople create detailed floor plans tailored to your needs. Every square foot is planned to create practical, comfortable living.
3. Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. We manage this entire process on your behalf, resolving any revision requests promptly.
4. Site Preparation and Foundation Work — Once permits are granted, on-site work kicks off. This includes grading the site, completing foundation work, and establishing utility connections.
5. Shell Construction and Exterior Finishing — 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 — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU operationally complete. All work is inspected 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 closing municipal review 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 clear categories. If you own a single-family home with available square footage under zoning rules, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families navigating multigenerational living situations.

You may also be someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Landlords and real estate investors 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 sites with unusual utility access challenges. Very small lots or properties with easements may require additional review. Brother & Brother Builders reviews each property on its own merits to advise you on what's feasible.

ADU Construction Frequently Asked Questions

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

The full timeline for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. Permitting alone can take two to four months in San Jose, so planning ahead matters. Simpler garage conversions often finish in the lower end of the range, while custom detached builds require more time.

What does ADU construction typically cost?

Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Attached ADU additions are generally priced lower, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a thorough property review.

Is ADU construction intrusive while it's underway?

How much the build affects daily life depends on whether you're converting existing space or building new. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Garage conversions or attached additions 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?

In most cases, you won't have to vacate your primary residence during ADU construction. Most builds are structured to allow you remain on the property throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the planning phase.

How long will an ADU built through professional ADU construction remain in good condition?

An ADU constructed with quality materials can be expected to last as long as the main residence — often several decades with routine maintenance. Longevity is tied to the systems installed, how well routine maintenance is performed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies commercial-grade materials and follow all code requirements to ensure lasting performance.

ADU Construction for Local Homeowners

San Jose's neighborhoods offer a variety of property types that are well suited for ADU construction. Residents in the Rose Garden district frequently see their parcels are well configured for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has likely worked nearby.

The City of San Jose's building department applies particular standards for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across the San Jose permitting environment means smoother project delivery from the first meeting to the final inspection.

Schedule Your ADU Construction Assessment Today

If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide licensed expertise check here in ADU construction for many different project types — from simple garage conversions to large custom detached cottages. The process begins with a thorough and honest property review where we understand your vision and share clear expectations of what ADU construction on your property will look like.

Get in touch with our office to schedule a site visit. No matter where you are in the decision-making process, our team is happy to answer questions, share examples of our work and give you the clarity you need to move forward. 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