Expand Your Home with Quality ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a versatile new living space on your existing property — whether you want to house a family member. Brother & Brother Builders has supported hundreds of local homeowners see these visions to life with precision and transparency.
The interest in ADU construction has grown rapidly in recent years, and it's not hard to see why. 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 address housing needs. 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 job. Our team is familiar with city and county requirements, the engineering requirements, and the aesthetic decisions that make an ADU truly livable. Should you want to learn about what ADU construction could do 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 fully independent living space — including a kitchen, bathroom, sleeping area, and its own entryway — 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 below-grade dwelling units.
Mechanically, the work starts with a thorough property evaluation, where our professionals evaluate property boundaries, available square footage, and infrastructure capacity. From there, design plans are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction transitions to the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a fully functional living unit attached to or separate from your main home.
What sets quality ADU construction apart is the level of craftsmanship at every stage. Components should be specified to match the primary home's aesthetic. Systems like plumbing and electrical must be built for long-term residential demand. Brother & Brother Builders treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Advantages ADU Construction
- Increased Property Value — ADU construction delivers real market value to your property, often generating strong equity gains when it's time to sell.
- Revenue Generation — A completed ADU is leasable as a long-term rental or short-term vacation unit, creating ongoing passive income for the homeowner.
- Space for Loved Ones — ADU construction gives aging parents a self-contained residence without leaving the property.
- Personalized Layouts — From open-plan one-bedrooms, ADU construction can be tailored to the intended occupant's lifestyle.
- Faster Permitting in California — Recent state legislation has cut down the permitting obstacles associated with ADU construction, resulting in a timeline that is faster and less expensive than ever before.
- Responsible Property Development — Building an ADU uses your existing lot instead of consuming open land, which aligns with sustainability goals.
- Independent Living Areas — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU remains an asset for many years and generates both functional space and financial upside.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our team visits your property to evaluate setbacks, lot coverage limits, and utility connections. This stage clarifies exactly what can be built before any time is invested in drawings.
- Custom Design and Architectural Planning — Licensed architects and designers create comprehensive blueprints tailored to your needs. Layouts are carefully considered to optimize daily use.
- 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, resolving any revision requests promptly.
- Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This includes grading the site, pouring the concrete foundation, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Skilled tradespeople 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 — Trim, appliances, tile, and lighting are fitted and completed to the agreed design. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Good Candidate for ADU Construction?
Homeowners who benefit most from ADU construction typically fall into a few common profiles. If you have a residential property with a backyard, garage, or basement that could be converted, you're already a strong candidate. Homeowners hoping to offset mortgage costs through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a detached creative or business space that remains away from your family's daily life. Landlords and real estate investors who already own residential properties are also a natural fit for ADU construction, since the long-term value is proven.
Situations where ADU construction may not be the best first step 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 recommend the right path forward.
ADU Construction Common Questions Answered
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, depending on design complexity and how quickly approvals come through. The approval phase alone can take a significant portion of the overall timeline in San Jose, so starting early is important. Smaller detached units often finish in the lower end of the range, while multi-room detached cottages require more time.
What does ADU construction cost in San Jose?
Pricing depends on many factors based on whether it's a conversion or new construction. Locally, ADU construction typically ranges from $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes between $75,000 and $140,000. A precise cost projection can only be produced following a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The level of disruption depends on where the ADU is being built. New construction in the rear yard are typically less disruptive, since the construction zone is separate. Projects that connect to the main structure may require temporary access during key milestones. Brother & Brother Builders keeps you informed about what to expect at each stage.
Do I need to leave my home during ADU construction?
For the majority of homeowners, 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 construction timeline. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that require short-term access disruption. Our construction supervisors will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
Any ADU built to code with professional oversight can be expected to last as long as more info your primary home — often several decades with routine maintenance. Durability depends to the quality of materials used, whether the unit is properly cared for, and how proactively issues are resolved over time. Brother & Brother Builders specifies high-quality components and comply with all local building codes to protect your investment for the long haul.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a diverse mix of property types that are well suited for ADU construction. Property owners near the Almaden Valley area have found their lots are well configured for ADU builds. The Berryessa area have seen growing ADU activity as multigenerational living becomes more common. From neighborhoods near the Guadalupe River Park corridor to those near Branham Lane, our team has likely worked nearby.
The City of San Jose's building department has developed specific protocols for ADU construction that our team navigates routinely. Proximity to transit corridors can affect how quickly permits are approved for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means more accurate timelines and budgets from kickoff through certificate of occupancy.
Start Your ADU Construction Planning Session Today
If you're ready to move forward with ADU construction, Brother & Brother Builders is here to help. Our experts offer licensed expertise 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 learn what you're trying to accomplish and share clear expectations of what's achievable.
Reach out to our team to set up your consultation. 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. This type of project is a meaningful commitment — and we're committed to helping you get it right.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632