Expand Your Home with Professional ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects 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 streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have embraced 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 works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering considerations, and the design choices that make an ADU truly livable. When you're ready to explore what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction involves 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 sits on the same property as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even below-grade dwelling units.
Mechanically, the work starts with a thorough property evaluation, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit connected to or independent of 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 match the primary home's aesthetic. Systems like plumbing and electrical must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable 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, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a self-contained residence without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction can be tailored to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of expanding urban sprawl, which contributes to sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any time is invested in drawings.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints based on your goals. Every square foot is planned to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Ground Prep and Structural Base — Once permits are issued, the build starts. This covers land preparation, laying the structural base, and setting up utilities.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
- Interior Systems and Infrastructure — Skilled tradespeople install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to the approved plan. A last official inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few recognizable groups. If you own a single-family home with available square footage under zoning rules, you're already well-positioned. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
Another strong candidate is someone who runs a small business and wants a separate office or studio space that is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include properties with significant setback limitations. Sites with underground infrastructure conflicts may require additional review. Our team can assess each property individually and honestly to recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and local permitting timelines. Permitting alone can take several months in San Jose, so planning ahead matters. Smaller detached units can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on whether it's a conversion or new construction. For most projects in this region, ADU construction generally falls between $150,000 to $400,000 or more for a fully custom construction. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be produced following a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. Standalone ADU projects are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may require temporary access during certain phases of construction. We provide advance notice about any phases that may affect your routine.
Do I need to move out during ADU construction?
In most cases, you are not required to vacate your main home during ADU construction. The vast majority of projects are set up to let you continue living in the home throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction hold up?
Any ADU built to code with professional oversight is designed to last as long as the main residence — often several decades with routine maintenance. How long it lasts comes down to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a wide range of property types that are well suited for ADU construction. Residents in the Rose Garden district often discover their properties accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
San Jose's permitting office follows defined procedures for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we listen to your goals and provide an honest assessment of what the project will involve.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, read more we're glad 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 we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632