Transform Your Property with Quality ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction provides a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners bring these projects to life with skill and transparency.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law has streamlined permitting for homeowners to add these secondary units, and local municipalities like San Jose have encouraged 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 provides increased control over how your property functions.
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 details, and the design choices that make an ADU functional. If you've been thinking about 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 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 — including a kitchen, bathroom, sleeping area, and its own entryway — that is located on the same parcel as a primary residence. ADU construction can take several forms, 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 professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. 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 wiring and water supply must be built for long-term residential demand. Brother & Brother Builders approaches every build with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction adds measurable market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU may be listed 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 comfortable home of their own without moving to another neighborhood.
- Design Flexibility — From modern studio layouts, ADU construction is adaptable to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has minimized the barriers and delays associated with ADU construction, making the process that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which supports broader sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where residents have their own space.
- 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 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 stage clarifies exactly what's possible before any resources go toward planning.
- 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.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. During this step, the ADU takes its visible shape.
- MEP Systems Rough-In — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU fully functional. Inspections are completed at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Countertops, hardware, finishes, and fixtures are placed and inspected to the agreed design. A closing municipal review issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Homeowners who benefit most from ADU construction generally fit within a few clear categories. If you own a single-family home with available square footage under zoning rules, you're already in a good starting place. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
You may also be someone who works from home and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who are building a portfolio are also well suited for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include sites with unusual utility access challenges. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property on its own merits to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction commonly spans six to fourteen months, depending on design complexity and local permitting timelines. City review on its own can take several months in San Jose, so planning ahead matters. Simpler garage conversions can move faster, while multi-room detached cottages take longer to complete.
What does ADU construction typically cost?
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 adu construction a fully custom construction. Interior conversion projects tend to cost less, sometimes between $75,000 and $140,000. An accurate budget can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are generally the least intrusive, since work happens away from the main house. Interior conversions may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about upcoming work and timelines.
Do I need to move out during ADU construction?
For the majority of homeowners, you do not need to vacate your primary residence 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 walk you through any potential disruptions during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
A well-built ADU can be expected to last as long as any standard residential structure — typically 50 years or more. Durability depends to the standard of construction, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. We select high-quality components and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a wide range of property types that are well suited for ADU construction. Residents in the Rose Garden district frequently see their parcels accommodate detached backyard units nicely. The Berryessa area have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team knows the permitting landscape well.
San Jose's permitting office follows defined procedures 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 the San Jose permitting environment means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Consultation Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is the team to call. Our builders provide licensed expertise in ADU construction for many different project types — from small attached additions to fully independent secondary homes. 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.
Reach out to our team to schedule a site visit. No matter where you are in the decision-making process, we're glad to walk through your options, review completed projects and give you the clarity you need to move forward. Building an ADU is a major decision — 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