Unlock New Space with Quality ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a flexible 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 skill and transparency.
The demand for ADU construction has grown rapidly in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to add these secondary units, and local municipalities like San Jose have encouraged the trend as a way to expand the housing supply. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property works.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering considerations, and the planning steps that make an ADU functional. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of designing, permitting, and building 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 entrance — 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 below-grade dwelling units.
Mechanically, the process begins with a comprehensive review of your lot, where our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the local building department. Once permits are secured, ADU construction transitions to the physical build phase — which includes foundation work, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit adjacent to or detached from your main home.
What sets quality ADU construction apart is the attention to detail at every stage. Materials must be selected to align with the neighborhood's character. Systems like HVAC and drainage more info must be sized for independent daily use. Brother & Brother Builders approaches every build with the same technical discipline we bring to full 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 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 offers family members a private, independent living space without losing proximity to the family.
- Customization Options — From open-plan one-bedrooms, ADU construction is adaptable to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Efficient Use of Your Lot — Building an ADU uses your existing lot instead of requiring new development, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Lasting Financial Benefit — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review 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 money is spent on design.
- Blueprint Development and Layout Design — Our design team create precise architectural drawings tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for inspection and clearance. We manage this entire process on your behalf, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are issued, the build starts. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Inspections are completed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A final city inspection issues the certificate of occupancy and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
People who see the greatest return from ADU construction often belong to a few clear categories. If you have a residential property with available square footage under zoning rules, you're already a strong candidate. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families navigating multigenerational living situations.
ADU construction also suits someone who works from home and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size thresholds. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction Common Questions Answered
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 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 require more time.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. Locally, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions tend to cost less, sometimes between $75,000 and $140,000. A detailed estimate can only be given after completing a full site assessment.
Is ADU construction intrusive while it's underway?
How much the build affects daily life depends on whether you're converting existing space or building new. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Garage conversions or attached additions may require temporary access during key milestones. We provide advance notice about upcoming work and timelines.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you won't have to vacate your main home during ADU construction. The vast majority of projects are designed so that you stay in your primary unit throughout the process. There are edge cases if major utility upgrades affect the main house in ways that briefly affect habitability. Our project managers will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
An ADU constructed with quality materials can be expected to last as long as the main residence — often several decades with routine maintenance. Durability depends to the standard of construction, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use high-quality components and follow all code requirements to ensure lasting performance.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a wide range of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels are well configured for ADU builds. Communities around the Capitol Expressway corridor 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 knows the permitting landscape well.
Local regulatory bodies in this area follows defined procedures for ADU construction that our team navigates routinely. Access to infrastructure along thoroughfares like Monterey Road can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide years of hands-on experience in ADU construction for many different project types — from modest studio builds to large custom detached cottages. The process begins with a detailed, no-pressure consultation where we listen to your goals and provide an honest assessment of what the project will involve.
Reach out to our team to set up your consultation. 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. ADU construction is a significant investment — 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