Unlock New Space with Quality ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the smartest investments they can make. ADU construction provides a versatile 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 care.
The demand for ADU construction has surged in recent years, and it's not hard to see 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 increase density responsibly. If you're planning a detached backyard cottage, a garage conversion, or an attached addition, ADU construction offers greater control over how your property serves your household.
At Brother & Brother Builders, we bring years of hands-on experience to every ADU construction build. Our team knows the San Jose building codes, the engineering considerations, and the design choices that make an ADU beautiful. Should you want to learn about 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 engineering, filing for, and completing 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 can take several forms, including detached backyard units, attached additions, garage conversions, and even interior space reconfigurations.
Mechanically, the process begins with a comprehensive review of your lot, where our team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the city for permit approval. Once the paperwork is cleared, ADU construction moves into the physical build phase — which encompasses site preparation, 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. Products need to be chosen to complement the existing structure. 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 bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction delivers real market value to your property, often increasing appraised value substantially when it's time to sell.
- Rental Income Potential — A completed ADU can be rented as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a self-contained residence without leaving the property.
- Design Flexibility — From modern studio layouts, ADU construction may be customized to your household's priorities.
- Simplified Regulatory Path — Recent state legislation has minimized the red tape associated with ADU construction, resulting in a timeline that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of requiring new development, which aligns with sustainability goals.
- Privacy for All Residents — 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 functional space and financial upside.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any resources go toward planning.
- Custom Design and Architectural Planning — Our design team create comprehensive blueprints based on your goals. Space is thoughtfully allocated to create practical, comfortable living.
- Permitting and City Approval — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. We manage this entire process on your behalf, resolving any revision requests promptly.
- Excavation and Foundation Installation — Once permits are issued, on-site work kicks off. This includes grading the site, laying the structural base, and establishing utility connections.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. During this step, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Certified technicians install the heating, cooling, drainage, and power infrastructure that make the ADU ready for occupancy. Inspections are completed at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the agreed design. A final city inspection confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction often belong to a few recognizable groups. If you are a homeowner with enough lot space to meet setback requirements, you're already well-positioned. Homeowners wanting to add a revenue stream through rental are among the most common ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a private work environment that is distinct from your family's daily life. Property investors and rental owners who want to maximize their land are also a natural fit for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include sites with unusual utility access challenges. Parcels in historic districts or HOA-restricted communities may face additional constraints. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction typically take from start to finish?
The total process for ADU construction typically ranges from six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take several months in San Jose, so beginning the process sooner rather than later is wise. Straightforward interior conversions may complete more quickly, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on project complexity and finishes selected. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Interior conversion projects tend to cost less, sometimes starting around $80,000 depending on scope. A precise cost projection can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are generally the least intrusive, since the construction zone is separate. Garage conversions or attached additions may create short-term inconveniences during key milestones. Our team communicates clearly about upcoming work and timelines.
Do I need to vacate the property during ADU construction?
In most cases, you do not need to vacate your main home during ADU construction. Most job sites are structured to allow you remain on the property throughout the build. Exceptions may arise if interior conversion work touches shared systems in ways that temporarily impact livability. Our construction supervisors will discuss these scenarios during the planning phase.
How long will an ADU built through professional ADU construction last?
A well-built ADU is designed to last as long as the main residence — often several decades with routine maintenance. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and whether systems like roofing and plumbing are serviced regularly. Brother & Brother Builders specifies high-quality components and follow all code requirements to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood frequently see their parcels are well configured get more info for ADU builds. Neighborhoods near Blossom Hill Road are increasingly popular for ADU construction as multigenerational living becomes more common. If you're located closer to Evergreen, our team has likely worked nearby.
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 affect how quickly permits are approved for a given ADU project. Our team's knowledge of these local conditions means more accurate timelines and budgets from kickoff through certificate of occupancy.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to move forward with ADU construction, Brother & Brother Builders is the team to call. Our experts offer licensed expertise in ADU construction across a wide range of project types — from small attached additions to multi-room backyard residences. Our approach opens with a thorough and honest property review where we listen to your goals and provide an honest assessment of what's achievable.
Get in touch with our office to begin the conversation. No matter where you are in the decision-making process, we enjoy answer questions, share examples of our work and help you take the next step. 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