Unlock New Space with Professional ADU Construction
Families in San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction creates 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 skill and integrity.
The demand for ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. 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 draw on extensive hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. When you're ready to explore what ADU construction could mean for your property, this guide explains everything you need to know.
What Is an ADU Build?
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 access point — that sits on the same property as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, everything kicks off with a thorough property evaluation, where our builders evaluate setbacks, zoning, utility access, and structural feasibility. From there, design plans are prepared and submitted to the local building department. 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. Components should be specified to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we use on major custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU may be listed 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.
- Design Flexibility — From open-plan one-bedrooms, ADU construction is adaptable to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the red tape associated with ADU construction, resulting in a timeline 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.
- 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 continues to produce returns for many years and generates both functional space and financial upside.
The ADU Construction Journey Step by Step
- Property Walkthrough and Feasibility Check — Our experts review your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any resources go toward planning.
- Custom Design and Architectural Planning — Experienced draftspeople create comprehensive blueprints based on your goals. Space is thoughtfully allocated to maximize function and livability.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for review and approval. Our team handles all submissions on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are approved, physical construction begins. This covers land preparation, completing foundation work, and running initial plumbing and electrical conduits.
- Shell Construction and Exterior Finishing — Framing is completed followed by roofing, siding, windows, and exterior doors. At this stage, the ADU transforms from a concept to a building.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Trim, appliances, tile, and lighting are placed and inspected to the agreed design. A closing municipal review issues the certificate of occupancy and the ADU is ready for use.
Who Is a Right Fit for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few recognizable groups. If you own a single-family home 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 supporting elderly parents.
ADU construction also suits someone who runs a small business and wants a separate office or studio space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited for ADU construction, since the return on investment is well-documented.
Situations where ADU construction may not be the best first step include lots that are below minimum size thresholds. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property individually and honestly to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The full timeline for ADU construction commonly spans six to fourteen months, depending on design complexity and city review schedules. The approval phase alone can take several months in San Jose, so starting early is important. Smaller detached units can move faster, while larger new construction ADUs take longer to complete.
What does ADU construction typically cost?
Costs vary widely based on whether it's a conversion or new construction. In the San Jose area, ADU construction generally falls between $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions often come in under, sometimes in the $80,000 to $150,000 range. An accurate budget can only be given after completing a full site assessment.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since work happens away from the main house. Projects that connect to the main structure may involve some shared wall work during specific stages like framing or MEP rough-in. We provide advance notice about what to expect at each stage.
Do I need to vacate the property during ADU construction?
For the majority of homeowners, you won't have to vacate your house during ADU construction. Most job sites are set up to let you remain on the property throughout the construction timeline. Exceptions may arise if interior conversion work touches shared systems in ways that require short-term access disruption. Our project managers will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
A well-built ADU is designed to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the systems installed, 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 follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a diverse mix of property types that are ideally positioned for check here ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as housing demand rises. 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 require a builder familiar with local expectations. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means fewer surprises from the first meeting to the final inspection.
Book Your ADU Construction Planning Session Today
If you're ready to add an ADU to your property, Brother & Brother Builders is here to help. We bring years of hands-on experience in ADU construction including all types of project types — from simple garage conversions to multi-room backyard residences. Every project starts with a comprehensive site assessment where we understand your vision and give you a realistic picture of what ADU construction on your property will look like.
Get in touch with our office to schedule a site visit. Even if you're just exploring the idea, we enjoy walk through your options, review completed projects and make sure you feel confident before committing. ADU construction is a significant investment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632