Expand Your Home with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a powerful new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners turn these plans to life with precision and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. 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 expand the housing supply. Whether you want to build 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 apply deep hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering considerations, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could look like on your property, this guide will walk you through everything you need to know.
What Is an ADU Build?
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 — featuring a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, everything kicks off with a detailed site assessment, where our builders evaluate lot dimensions, existing structures, soil conditions, and local code requirements. read more From there, design plans 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, roofing, plumbing, electrical, insulation. The result is a completely finished living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Components should be specified to complement the existing structure. Systems like HVAC and drainage must be designed to handle full-time occupancy. Brother & Brother Builders treats each project with the same professional rigor we bring to full custom home projects.
Key Advantages ADU Construction
- Higher Resale Potential — 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 can be rented as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a private, independent living space without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has cut down the red tape associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of consuming open land, which supports broader sustainability goals.
- Separate Entrances and Spaces — 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 remains an asset for decades, providing both usable housing and equity growth.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Experienced draftspeople create detailed floor plans tailored to your needs. Space is thoughtfully allocated to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose demands documentation to the city's building department for review and approval. Our team handles all submissions on your behalf, addressing any city comments promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This involves leveling and prepping the ground, completing foundation work, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by roofing, siding, windows, and exterior doors. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. All work is inspected at designated stages throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A final city inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within a few recognizable groups. If you are a homeowner 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 motivated ADU construction clients, along with families accommodating adult children who need housing.
ADU construction also suits someone who works from home and wants a separate office or studio space that is distinct from your family's daily life. Landlords and real estate investors who are building a portfolio are also a natural fit for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include properties with significant setback limitations. Sites with underground infrastructure conflicts may need a modified approach. Brother & Brother Builders reviews each property individually and honestly to advise you on what's feasible.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, based on the project scope and how quickly approvals come through. The approval phase alone can take several months in San Jose, so planning ahead matters. Straightforward interior conversions often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on the type and size of the ADU. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a detached new build. Interior conversion projects are generally priced lower, sometimes starting around $80,000 depending on scope. An accurate budget can only be given after completing a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
The level of disruption depends on the project's location on your property. Detached backyard builds are typically less disruptive, since the construction zone is separate. Interior conversions may require temporary access during specific stages like framing or MEP rough-in. 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 won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you remain on the property throughout the construction timeline. There are edge cases if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
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 the main residence — typically 50 years or more. Longevity is tied to the quality of materials used, how well routine maintenance is performed, and how proactively issues are resolved over time. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to ensure lasting performance.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a diverse mix of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as families expand. Whether your property is near downtown San Jose, our team has project experience in the area.
Local regulatory bodies in this area applies particular standards for ADU construction that our team navigates routinely. Proximity to transit corridors 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 kickoff through certificate of occupancy.
Schedule Your ADU Construction Consultation Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer proven skills in ADU construction for many different project types — from simple garage conversions to multi-room backyard residences. The process begins with a detailed, no-pressure consultation where we listen to your goals and give you a realistic picture of what the project will involve.
Reach out to our team to schedule a site visit. Even if you're just exploring the idea, our team is happy to answer questions, share examples of our work and help you take the next step. 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