Expert ADU Construction Services for Homeowners

Expand Your Home with Professional ADU Construction

Families in San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with craftsmanship and integrity.

The demand for ADU construction has grown rapidly in recent years, and it's no mystery. 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 expand the housing supply. 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 considerations, and the design choices that make an ADU functional. 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 involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — including a kitchen, bathroom, sleeping area, and its own entrance — that sits on the same property 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 process begins with a detailed site assessment, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the city for permit approval. Once approvals are in place, ADU construction enters the physical build phase — which covers everything from foundational 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 sets quality ADU construction apart is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.

Key Reasons to Choose 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.
• 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.
• Multi-Generational Living — ADU construction offers family members a self-contained residence without losing proximity to the family.
• Personalized Layouts — From two-bedroom configurations, ADU construction can be tailored to your household's priorities.
• Streamlined Approval Process — Recent state legislation has cut down 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 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 delivers a genuinely independent unit where residents have their own space.
• 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 evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what's possible before any money is spent on design.
2. Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
3. Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. We manage this entire process on your behalf, addressing any city comments promptly.
4. Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
5. Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. At this stage, the ADU transforms from a concept to a building.
6. Interior Systems and Infrastructure — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
7. Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are installed and finished to your specifications. A final city inspection grants legal occupancy status and the ADU is ready for use.

Who Is a Right Fit for ADU Construction?

Property owners who are best suited from ADU construction often belong to a few common profiles. If you own a single-family home with enough lot space to meet setback requirements, you're already a strong candidate. 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.

Another strong candidate is someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio are also prime candidates for ADU construction, since the return on investment is well-documented.

Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may face additional constraints. Our team can assess each property on its own merits to advise you on what's feasible.

ADU Construction Common Questions Answered

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

The full timeline for ADU construction commonly spans six to fourteen months, based on the project scope and local permitting timelines. Permitting alone can take two to four months in San Jose, so starting early is important. Smaller detached units can move faster, while custom detached builds fall toward the upper end of the timeline.

What does ADU construction cost in San Jose?

Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Garage conversions are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be developed after a thorough property review.

Is ADU construction difficult to live through while it's underway?

The level of disruption depends on whether you're converting existing space or building new. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. Our team communicates clearly about what to expect at each stage.

Do I need to move out during ADU construction?

Generally speaking, you do not need to vacate your primary residence during ADU construction. Most job sites are designed so that you remain on the property throughout the process. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that temporarily impact livability. Our project managers will walk you through any potential disruptions during the planning phase.

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. Durability depends here to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. Our builds use high-quality components and comply with all local building codes to protect your investment for the long haul.

ADU Construction for San Jose 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 accommodate detached backyard units nicely. The Berryessa area are increasingly popular for ADU construction as housing demand rises. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.

Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. 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 this region's building landscape means fewer surprises from design through the final walkthrough.

Start Your ADU Construction Planning Session Today

If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU construction across a wide range of project types — from simple garage conversions to large custom detached cottages. Our approach opens with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what ADU construction on your property will look like.

Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, our team is happy to discuss timelines, costs, and design possibilities and help you take the next step. Building an ADU is a major decision — and we're committed to helping you get it right.

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