Expand Your Home with Expert ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most practical investments they can make. ADU construction opens the door to a powerful 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 craftsmanship and transparency.
The demand for ADU construction has increased significantly in recent years, and it's no mystery. California state law now makes it easier for homeowners to construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to address housing needs. Whether you're building 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 apply deep hands-on experience to every ADU construction project. Our team understands the local permitting process, the engineering requirements, and the planning steps that make an ADU beautiful. Should you want to learn about what ADU construction could mean for your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction refers to 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 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 basement or interior conversions.
Mechanically, the process begins with a comprehensive review of your lot, 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 enters 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 separates excellent ADU construction from an average project 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 treats each project with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Increased Property Value — ADU construction adds measurable market value to your property, often increasing appraised value substantially 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, creating ongoing passive income for the homeowner.
- Multi-Generational Living — ADU construction offers family members a comfortable home of their own without losing proximity to the family.
- Design Flexibility — 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 barriers and delays associated with ADU construction, making the process that is faster and more affordable than ever before.
- Responsible Property Development — Building an ADU maximizes the land you already own instead of expanding urban sprawl, which aligns with sustainability goals.
- Privacy for All Residents — Unlike a bedroom addition, ADU construction delivers a genuinely independent unit where residents have their own space.
- Lasting Financial Benefit — A well-built ADU holds its value for the long haul by offering both livable square footage and monetary benefit.
The ADU Construction Journey Step by Step
- Initial Property Assessment and Feasibility Review — Our experts review your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what ADU types will work before any time is invested in drawings.
- Blueprint Development and Layout Design — Licensed architects and designers create precise architectural drawings tailored to your needs. Layouts are carefully considered to create practical, comfortable living.
- Permit Submission and Municipal Review — ADU construction in San Jose involves filing drawings to the city's building department for sign-off and verification. We manage this entire process on your behalf, responding to review feedback promptly.
- Site Preparation and Foundation Work — Once permits are approved, physical construction begins. This involves leveling and prepping the ground, pouring the concrete foundation, and setting up utilities.
- Structural Framing and Weatherproofing — Walls and roof systems go up followed by weatherproofing and exterior finish materials. At this stage, the ADU becomes recognizable as a structure.
- Interior Systems and Infrastructure — Certified technicians install the water supply, drain lines, and electrical panel that make the ADU operationally complete. All work is inspected at designated stages throughout ADU construction.
- Interior Finishing and Final Inspections — Countertops, hardware, finishes, and fixtures are fitted and completed to the approved plan. 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?
Homeowners who benefit most from ADU construction generally fit within 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 looking to generate income through rental are among the most motivated ADU construction clients, along with families accommodating adult children who need housing.
Another strong candidate is someone who needs a dedicated professional workspace and wants a private work environment that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also prime candidates for ADU construction, since the long-term value is proven.
Those who should discuss alternatives first include properties with significant setback limitations. Very small lots or properties with easements may face additional constraints. Our experts will evaluate each property on its own merits to recommend the right path forward.
ADU Construction Frequently Asked Questions
How long does ADU construction usually take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, influenced by the type of unit being built and local permitting timelines. Permitting alone can take several months in San Jose, so planning ahead matters. Simpler garage conversions may complete more quickly, while multi-room detached cottages fall toward the upper end of the timeline.
What does ADU construction typically cost?
Costs vary widely based on the type and size of the ADU. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a standalone backyard unit. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A detailed estimate can only be produced following a thorough property review.
Is ADU construction difficult to live through while it's underway?
The day-to-day impact depends on where the ADU is being built. Standalone ADU projects are usually easier to live alongside, since work happens away from the main house. Interior conversions may create short-term inconveniences during specific stages like framing or MEP rough-in. Our team communicates clearly about upcoming work and timelines.
Do I need to move out during ADU construction?
Generally speaking, you do not need to vacate your primary residence during ADU construction. Most builds are set up to let you remain on the property throughout the construction timeline. Exceptions may arise if major utility upgrades affect the main house in ways that temporarily impact livability. Our project managers will walk you through any potential disruptions 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 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 read more roofing and plumbing are serviced regularly. Our builds use high-quality components and build to current California residential standards to deliver a structure that stands the test of time.
ADU Construction for Local Homeowners
The communities throughout San Jose provide a variety 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. Communities around the Capitol Expressway corridor are increasingly popular for ADU construction as families expand. Whether your property is near downtown San Jose, our team knows the permitting landscape well.
The City of San Jose's building department follows defined procedures 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 the San Jose permitting environment means more accurate timelines and budgets from the first meeting to the final inspection.
Schedule Your ADU Construction Planning Session Today
Should you be thinking about how to add an ADU to your property, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction including all types of project types — from simple garage conversions to large custom detached cottages. Every project starts with a comprehensive site assessment where we learn what you're trying to accomplish and give you a realistic picture of what ADU construction on your property will look like.
Reach out to our team to schedule a site visit. Whether you're in the early stages of planning, our team is happy to discuss timelines, costs, and design possibilities and give you the clarity you need to move forward. 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