Brother & Brother Builders

Transform Your Property with Quality ADU Construction

Families in San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a flexible new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with craftsmanship and care.

The demand for ADU construction has increased significantly in recent years, and it's not hard to see why. California state law has simplified the process for homeowners to construct these secondary units, and local municipalities like San Jose have embraced 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 offers greater control over how your property functions.

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 requirements, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could look like on your property, this guide covers everything you need to know.

What Is the ADU Construction Process?

ADU construction describes the process of planning, approving, and constructing 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 entrance — that is located on the same parcel as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.

Mechanically, everything kicks off 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 local building department. Once permits are secured, ADU construction enters the physical build phase — which covers everything from foundational work, framing, HVAC, drywall, flooring, and exterior finishes. The result is a completely finished living unit attached to or separate from 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 complement the existing structure. 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 technical discipline we bring to full custom home projects.

Key Advantages ADU Construction

• Increased Property Value — ADU construction adds measurable market value to your property, often returning more than the build cost 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 provides adult children a self-contained residence without leaving the property.
• Personalized Layouts — From modern studio layouts, ADU construction may be customized to your household's priorities.
• Streamlined Approval Process — Recent state legislation has minimized the barriers and delays associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
• Responsible Property Development — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which contributes to sustainability goals.
• Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
• Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both functional space and financial upside.

The ADU Construction Procedure Step by Step

1. Property Walkthrough and Feasibility Check — 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 reflecting your priorities. Layouts are carefully considered to optimize daily use.
3. Permitting and City Approval — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
4. Excavation and Foundation Installation — Once permits are granted, physical construction begins. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
5. Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by weatherproofing and exterior finish materials. This phase, the ADU takes its visible shape.
6. Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
7. Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are fitted and completed to your specifications. A last official inspection grants legal occupancy status and your new space is cleared for use.

Who Is a Good Candidate for ADU Construction?

Property owners who are best suited from ADU construction often belong to a few clear categories. If you own a single-family home with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.

Another strong candidate is someone who runs a small here business and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who want to maximize their land are also well suited 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. 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 FAQ

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

The full timeline for ADU construction typically ranges from six to fourteen months, depending on design complexity and local permitting timelines. 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 often finish in the lower end of the range, while multi-room detached cottages fall toward the upper end of the timeline.

What does ADU construction usually run in terms of budget?

Budget requirements differ based on project complexity and finishes selected. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.

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. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may create short-term inconveniences during certain phases of construction. Brother & Brother Builders keeps you informed about what to expect at each stage.

Do I need to leave my home during ADU construction?

Generally speaking, you do not need to vacate your main home during ADU construction. The vast majority of projects are structured to allow you remain on the property throughout the process. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. Our project managers will walk you through any potential disruptions during the pre-construction consultation.

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

An ADU constructed with quality materials is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the systems installed, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Our builds use residential-grade products rated for longevity and follow all code requirements to deliver a structure that stands the test of time.

ADU Construction for Local Homeowners

The communities throughout San Jose provide a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area often discover their properties are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction as families expand. If you're located closer to Evergreen, our team has likely worked nearby.

San Jose's permitting office has developed specific protocols for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from the first meeting to the final inspection.

Schedule Your ADU Construction Consultation Today

Should you be thinking about how 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 including all types of project types — from modest studio builds to fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation where we understand your vision and share clear expectations of what ADU construction on your property will look like.

Reach out to our team to begin the conversation. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. 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