Expand Your Home with Expert ADU Construction
Homeowners across San Jose, CA are discovering 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 turn these plans to life with precision and transparency.
The popularity of ADU construction has increased significantly in recent years, and it's no mystery. California state law has streamlined permitting for homeowners to construct these secondary units, and local municipalities like San Jose have supported 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 works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering considerations, and the design choices that make an ADU functional. When you're ready to explore 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 refers to 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 — featuring a kitchen, bathroom, sleeping area, and its own access point — 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 team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the relevant municipal authority. Once approvals are in place, ADU construction transitions to the physical build phase — which covers everything from foundational work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the attention to detail at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like HVAC and drainage must be sized for independent daily use. Brother & Brother Builders treats each project with the same professional rigor we use on major custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction contributes significant 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 gives aging parents a private, independent living space without leaving the property.
- Personalized Layouts — From two-bedroom configurations, ADU construction may be customized to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, making the process that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU works within your current footprint instead of expanding urban sprawl, which supports broader sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any money is spent on design.
- Custom Design and Architectural Planning — Licensed architects and designers create detailed floor plans tailored to your needs. Layouts are carefully considered to optimize daily use.
- Permitting and City Approval — 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, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, the build starts. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Shell Construction and Exterior Finishing — Walls and roof systems go up followed by insulation, sheathing, and exterior cladding. During this step, the ADU transforms from a concept to a building.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A last official inspection confirms the unit is code-compliant and the ADU is ready for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from read more ADU construction typically fall into a few common profiles. If you have a residential property with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners looking to generate income through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who runs a small business and wants a separate office or studio space 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 rental income frequently offsets build costs.
Homeowners who may want to pause and evaluate include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may need a modified approach. Our team can assess each property on its own merits to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The total process for ADU construction commonly spans six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions can move faster, while larger new construction ADUs require more time.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Interior conversion projects often come in under, sometimes between $75,000 and $140,000. A precise cost projection can only be given after completing a thorough property review.
Is ADU construction difficult to live through while it's underway?
How much the build affects daily life depends on the project's location on your property. Standalone ADU projects are generally the least intrusive, since the construction zone is separate. 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 vacate the property during ADU construction?
In most cases, you are not required to vacate your main home during ADU construction. Most builds are designed so that you continue living in the home throughout the build. Certain situations could require a brief departure if significant structural connections require temporary shutoffs in ways that require short-term access disruption. The team at Brother & Brother Builders will flag these situations during the planning phase.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials should last as long as any standard residential structure — indefinitely with proper upkeep. Longevity is tied to the standard of construction, how consistently minor repairs are addressed, and how proactively issues are resolved over time. Our builds use 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
San Jose's neighborhoods offer a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. Whether your property is near downtown San Jose, our team has likely worked nearby.
Local regulatory bodies in this area follows defined procedures for ADU construction that our team navigates routinely. Location near major arterials like Story Road or Tully Road can impact the design approach for a given ADU project. Our team's knowledge of the San Jose permitting environment means fewer surprises from kickoff through certificate of occupancy.
Book Your ADU Construction Planning Session Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our builders provide licensed expertise in ADU construction for many different project types — from modest studio builds to large custom detached cottages. The process begins with a thorough and honest property review where we understand your vision and provide an honest assessment of what ADU construction on your property will look like.
Get in touch with our office to set up your consultation. No matter where you are in the decision-making process, 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 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