Unlock New Space with Expert ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has guided hundreds of local homeowners see these visions to life with craftsmanship and integrity.
The interest in ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have supported 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 works.
At Brother & Brother Builders, we apply deep hands-on experience to every ADU construction build. Our team understands the local permitting process, the engineering details, and the planning steps that make an ADU functional. If you've been thinking about what ADU construction could mean for your property, this guide covers everything you need to know.
What Is the ADU Construction Process?
ADU construction involves the process of designing, permitting, and building an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — featuring a kitchen, bathroom, sleeping area, and its own access point — that exists on the same lot 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 work starts with a comprehensive review of your lot, where read more 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 transitions to the physical build phase — which encompasses site preparation, framing, roofing, plumbing, electrical, insulation. The result is a completely finished living unit attached to or separate from your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Products need to be chosen to complement the existing structure. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same high standards we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction delivers real market value to your property, often generating strong equity gains 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, providing a consistent income stream for the homeowner.
- Housing for Extended Family — ADU construction offers family members a self-contained residence without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction may be customized to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the permitting obstacles associated with ADU construction, making the process that is faster and less expensive 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 creates a truly separate unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for decades, providing both usable housing and equity growth.
The ADU Construction Journey Step by Step
- Site Evaluation and Zoning Analysis — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This phase answers exactly what's possible before any resources go toward planning.
- Blueprint Development and Layout Design — Experienced draftspeople create precise architectural drawings based on your goals. Layouts are carefully considered to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings 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 approved, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and establishing utility connections.
- Framing, Roofing, and Exterior Work — 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 plumbing lines, electrical wiring, and HVAC systems that make the ADU ready for occupancy. All work is inspected at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Flooring, cabinetry, fixtures, paint are placed and inspected to the agreed design. A last official inspection issues the certificate of occupancy and the unit is officially approved for use.
Who Is a Good Candidate for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few common profiles. If you own a single-family home with enough lot space to meet setback requirements, you're already in a good starting place. Homeowners hoping to offset mortgage costs through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a separate office or studio space that doesn't interfere with your family's daily life. Landlords and real estate investors who are building a portfolio 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. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our team can assess 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 commonly spans six to fourteen months, based on the project scope and city review schedules. Permitting alone can take a significant portion of the overall timeline in San Jose, so planning ahead matters. Smaller detached units often finish in the lower end of the range, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction usually run in terms of budget?
Costs vary widely based on project complexity and finishes selected. For most projects in this region, ADU construction generally falls between $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. A precise cost projection can only be produced following a formal feasibility evaluation.
Is ADU construction disruptive while it's underway?
The day-to-day impact depends on where the ADU is being built. New construction in the rear yard are generally the least intrusive, since work happens away from the main house. Projects that connect to the main structure may create short-term inconveniences during specific stages like framing or MEP rough-in. Brother & Brother Builders keeps you informed about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. Most builds are structured to allow you stay in your primary unit throughout the process. Exceptions may arise if major utility upgrades affect the main house in ways that briefly affect habitability. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
A well-built ADU can be expected to last as long as any standard residential structure — often several decades with routine maintenance. How long it lasts comes down to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Our builds use commercial-grade materials and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
San Jose's neighborhoods offer a variety of property types that are perfectly suited for ADU construction. Property owners near the Almaden Valley area often discover their properties accommodate detached backyard units nicely. The Berryessa area are seeing more homeowners add secondary units as families expand. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team knows the permitting landscape well.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our team's knowledge of this region's building landscape means smoother project delivery from the first meeting to the final inspection.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction for many different project types — from simple garage conversions to large custom detached cottages. Our approach opens with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture 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, our team is happy to answer questions, share examples of our work and make sure you feel confident before committing. This type of project is a meaningful commitment — 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