Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with craftsmanship and transparency.
The interest in ADU construction has surged in recent years, and it's not hard to see why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a garage conversion, or an attached addition, ADU construction provides increased control over how your property serves your household.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction project. Our team knows the San Jose building codes, the engineering requirements, and the planning steps that make an ADU truly livable. When you're ready to explore what ADU construction could do for your property, this guide explains everything you need to know.
What Is an ADU Build?
ADU construction involves the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring 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 interior space reconfigurations.
Mechanically, the process begins with a detailed site assessment, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the city for permit approval. 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 completely finished living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the depth of planning 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 handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — 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 can be rented 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 private, independent living space without losing proximity to the family.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to your specific needs.
- Simplified Regulatory Path — Recent state legislation has minimized the red tape 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 consuming open land, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction creates a truly separate unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This phase answers exactly what ADU types will work before any money is spent on design.
- Custom Design and Architectural Planning — Experienced draftspeople create precise architectural drawings tailored to your needs. Layouts are carefully considered to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This covers land preparation, laying the structural base, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Every system is reviewed at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are installed and finished to your specifications. A last official inspection grants legal occupancy status and the ADU is ready for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you have a residential property with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Real estate-minded homeowners who want to maximize their land are also a natural fit for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Our team can assess each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built get more info and local permitting timelines. City review on its own can take a significant portion of the overall timeline 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 typically cost?
Budget requirements differ 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 fully custom construction. Interior conversion projects tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be produced following a full site assessment.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are generally the least intrusive, since the crew operates at a distance from your living areas. Interior conversions 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 leave my home during ADU construction?
In most cases, you won't have to vacate your primary residence during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the process. There are edge cases if major utility upgrades affect the main house in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight should last as long as any standard residential structure — typically 50 years or more. Durability depends to the systems installed, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select residential-grade products rated for longevity and comply with all local building codes 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 frequently see their parcels are well configured for ADU builds. The Berryessa area are increasingly popular for ADU construction 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.
Local regulatory bodies in this area has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can impact the design approach for a given ADU project. Our familiarity with these local conditions means fewer surprises from design through the final walkthrough.
Start Your ADU Construction Consultation Today
When you want to add an ADU to your property, Brother & Brother Builders is here to help. Our experts offer licensed expertise in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. Every project starts with a thorough and honest property review where we learn what you're trying to accomplish and provide an honest assessment of what's achievable.
Reach out to our team to begin the conversation. No matter where you are in the decision-making process, we're glad to discuss timelines, costs, and design possibilities and help you take the next step. This type of project is a meaningful commitment — and we want to make sure it's the right one for you.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632