Transform Your Property with Expert ADU Construction
Property owners throughout San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with skill and care.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering considerations, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction describes the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — including a kitchen, bathroom, sleeping area, and its own entrance — 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 below-grade dwelling units.
Mechanically, the process begins with a thorough property evaluation, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, blueprints are prepared and submitted to the local building department. 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 move-in-ready living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Materials must be selected to align with the neighborhood's character. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Increased Property Value — ADU construction delivers real 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, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a self-contained residence without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to your specific needs.
- Faster Permitting in California — Recent state legislation has reduced 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 uses your existing lot instead of requiring new development, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- Long-Term Investment Security — A well-built ADU holds its value for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what's possible before any money is spent on design.
- Custom Design and Architectural Planning — Experienced draftspeople create detailed floor plans based on your goals. Every square foot is planned to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for sign-off and verification. We manage this entire process on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU operationally complete. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review issues the certificate of occupancy and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few recognizable groups. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families navigating multigenerational living situations.
You may also be someone who needs a dedicated professional workspace 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 well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may need a modified approach. 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 typically ranges from six to fourteen months, influenced by the type of unit being built and local permitting timelines. City review on its own can take several months in San Jose, so starting early is important. 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 get more info on whether it's a conversion or new construction. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a detached new build. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be developed after a formal feasibility evaluation.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may create short-term inconveniences during certain phases of construction. Our team communicates clearly about what to expect at each stage.
Do I need to leave my home during ADU construction?
Generally speaking, you won't have to vacate your house during ADU construction. Most job sites are designed so that you continue living in the home throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that briefly affect habitability. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies residential-grade products rated for longevity and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a wide range of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured for ADU builds. Neighborhoods near Blossom Hill Road have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
San Jose's permitting office follows defined procedures for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means more accurate timelines and budgets from design through the final walkthrough.
Start Your ADU Construction Assessment Today
When you want to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide proven skills in ADU construction including all types of project types — from modest studio builds to large custom detached cottages. Every project starts with a comprehensive site assessment where we listen to your goals and share clear expectations of what's achievable.
Reach out to our team to begin the conversation. Whether you're in the early stages of planning, we're glad to walk through your options, review completed projects and make sure you feel confident before committing. ADU construction is a significant investment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632