Unlock New Space with Expert ADU Construction
Homeowners across San Jose, CA are discovering that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction provides a versatile new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has guided hundreds of local homeowners bring these projects to life with craftsmanship and care.
The popularity of ADU construction has grown rapidly in recent years, and it's no mystery. California state law has simplified the process for homeowners to build 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 provides increased control over how your property serves your household.
At Brother & Brother Builders, we draw on extensive hands-on experience to every ADU construction build. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU beautiful. Should you want to learn 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 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 — equipped with a kitchen, bathroom, sleeping area, and its own access point — that is located on the same parcel as a primary residence. ADU construction comes in multiple configurations, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins with a detailed site assessment, where our team evaluate setbacks, zoning, utility access, and structural feasibility. From there, architectural drawings are prepared and submitted to the local building department. Once permits are secured, ADU construction enters the physical build phase — which encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a completely finished living unit connected to or independent of your main home.
The difference between a good and a great ADU build is the level of craftsmanship at every stage. Products need to be chosen to match the primary home's aesthetic. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same high standards we apply to large-scale custom home projects.
Key Benefits ADU Construction
- Boosted Home Equity — 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 may be listed as a long-term rental or short-term vacation unit, providing a consistent income stream for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a comfortable home of their own without moving to another neighborhood.
- Personalized Layouts — From modern studio layouts, ADU construction can be tailored to the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has cut down the permitting obstacles associated with ADU construction, making the process that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU works within your current footprint instead of consuming open land, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Durable Return on Investment — A well-built ADU holds its value for many years and generates both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — 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 detailed floor plans tailored to your needs. Space is thoughtfully allocated to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for sign-off and verification. Brother & Brother Builders coordinates the permitting on your behalf, addressing any city comments promptly.
- Excavation and Foundation Installation — Once permits are granted, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- Framing, Roofing, and Exterior Work — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Mechanical, Electrical, and Plumbing Installation — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. Inspections are completed at each code checkpoint throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A last official inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
People who see the greatest return from ADU construction typically fall into a few recognizable groups. If you are a homeowner 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 navigating multigenerational living situations.
Another strong candidate is someone who needs a dedicated professional workspace and wants a detached creative or business space that doesn't interfere with your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Homeowners who may want to pause and evaluate include lots that are below minimum size thresholds. Very small lots or properties with easements may require additional review. Our experts will evaluate 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 commonly spans six to fourteen months, based on the project scope and local permitting timelines. The approval phase alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions may complete more quickly, while multi-room detached cottages take longer to complete.
What does ADU construction usually run in terms of budget?
Budget requirements differ based on the type and size of the ADU. In the San Jose area, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects often come in under, sometimes starting around adu construction San Jose CA $80,000 depending on scope. An accurate budget can only be developed after a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. Standalone ADU projects are usually easier to live alongside, since the crew operates at a distance from your living areas. Projects that connect to the main structure may require temporary access during key milestones. We provide advance notice about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
In most cases, you do not need to vacate your primary residence during ADU construction. The vast majority of projects are structured to allow you continue living in the home throughout the construction timeline. There are edge cases if interior conversion work touches shared systems in ways that briefly affect habitability. Our project managers will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials can be expected to last as long as the main residence — 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. Brother & Brother Builders specifies residential-grade products rated for longevity and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area frequently see their parcels work well for both attached and detached projects. The Berryessa area are seeing more homeowners add secondary units as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.
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 affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across these local conditions means smoother project delivery from the first meeting to the final inspection.
Start Your ADU Construction Consultation Today
If you're ready to add an ADU to your property, Brother & Brother Builders is the team to call. Our builders provide proven skills in ADU construction for many different project types — from small attached additions to multi-room backyard residences. The process begins with a comprehensive site assessment where we listen to your goals and give you a realistic picture of what the project will involve.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, our team is happy to discuss timelines, costs, and design possibilities and make sure you feel confident before committing. 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