Expand Your Home with Expert ADU Construction
Property owners throughout San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest 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 guided hundreds of local homeowners bring these projects to life with craftsmanship and integrity.
The popularity of ADU construction has surged in recent years, and it's no mystery. California state law has simplified the process for homeowners to add these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. Whether you want to build a detached backyard cottage, a garage conversion, or an attached addition, ADU construction gives you more control over how your property serves your household.
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 details, and the planning steps that make an ADU beautiful. When you're ready to explore what ADU construction could do for your property, this guide will walk you through everything you need to know.
What Is the ADU Construction Process?
ADU construction involves 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 can take several forms, 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 lot dimensions, existing structures, soil conditions, and local code requirements. From there, design plans are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction enters the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the attention to detail at every stage. Products need to be chosen to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders treats each project with the same high standards we use on major custom home projects.
Key Advantages 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 can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction provides adult children a private, independent living space without moving to another neighborhood.
- Design Flexibility — From two-bedroom configurations, ADU construction is adaptable to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has minimized the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and more cost-efficient than ever before.
- Sustainable Land Use — Building an ADU uses your existing lot instead of consuming open land, which contributes to sustainability goals.
- Separate Entrances and Spaces — 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 the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits 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 precise architectural drawings based on your goals. Every square foot is planned to maximize function and livability.
- Filing for Building Permits — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. We manage this entire process on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Framing, Roofing, and Exterior Work — The structural frame is erected followed by weatherproofing and exterior finish materials. This phase, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. All work is inspected at each code checkpoint throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are placed and inspected to your specifications. A last official inspection grants legal occupancy status and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few clear categories. If you are a homeowner with enough lot space to meet setback requirements, you're already a strong candidate. Homeowners website wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
Another strong candidate is someone who runs a small business and wants a private work environment that doesn't interfere with your family's daily life. Property investors and rental owners who already own residential properties are also prime candidates for ADU construction, since the return on investment is well-documented.
Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may require additional review. Our team can assess each property on its own merits to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction typically ranges from six to fourteen months, influenced by the type of unit being built and how quickly approvals come through. The approval phase alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units can move faster, while custom detached builds require more time.
What does ADU construction cost in San Jose?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after 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. New construction in the rear yard 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 certain phases of construction. We provide advance notice 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 house during ADU construction. Most builds are set up to let you stay in your primary unit throughout the process. Exceptions may arise if significant structural connections require temporary shutoffs in ways that temporarily impact livability. The team at Brother & Brother Builders will discuss these scenarios during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight is designed to last as long as any standard residential structure — indefinitely with proper upkeep. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Our builds use residential-grade products rated for longevity and comply with all local building codes to deliver a structure that stands the test of time.
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. 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.
Local regulatory bodies in this area has developed specific protocols for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Our familiarity with these local conditions means smoother project delivery from design through the final walkthrough.
Book Your ADU Construction Consultation Today
When you want to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our builders provide years of hands-on experience in ADU construction across a wide range of project types — from simple garage conversions to large custom detached cottages. Our approach opens with a comprehensive site assessment where we listen to your goals and provide an honest assessment of what's achievable.
Reach out to our team 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. 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