Expand Your Home with Professional 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 helped hundreds of local homeowners see these visions to life with precision and integrity.
The popularity of 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 construct these secondary units, and local municipalities like San Jose have embraced the trend as a way to expand the housing supply. 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 bring years of hands-on experience to every ADU construction job. Our team knows the San Jose building codes, the engineering details, and the aesthetic decisions that make an ADU truly livable. If you've been thinking about what ADU construction could do 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 comes in multiple configurations, 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 our builders evaluate property boundaries, available square footage, and infrastructure capacity. From there, blueprints are prepared and submitted to the relevant municipal authority. Once the paperwork is cleared, ADU construction moves into the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit attached to or separate from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Components should be specified to align with the neighborhood's character. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders approaches every build with the same high standards we apply to large-scale custom home projects.
Key Benefits 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.
- Revenue Generation — 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 the intended occupant's lifestyle.
- Simplified Regulatory Path — Recent state legislation has reduced the barriers and delays 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.
- Lasting Financial Benefit — A well-built ADU continues to produce returns for decades, providing both livable square footage and monetary benefit.
The ADU Construction Procedure Step by Step
- Property Walkthrough and Feasibility Check — Our builders assess your property to evaluate setbacks, lot coverage limits, and utility connections. This step tells you exactly what's possible before any time is invested in drawings.
- Architectural Drafting and Space Planning — Licensed architects and designers create precise architectural drawings tailored to your needs. Every square foot is planned to optimize daily use.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are approved, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and running initial plumbing and electrical conduits.
- Structural Framing and Weatherproofing — Framing is completed followed by insulation, sheathing, and exterior cladding. This phase, the ADU takes its visible shape.
- Mechanical, Electrical, and Plumbing Installation — Skilled tradespeople install the water supply, drain lines, and electrical panel that make the ADU ready for occupancy. Every system is reviewed at required milestones throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are placed and inspected to the approved plan. 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?
People who see the greatest return from ADU construction often belong to a few clear categories. If you are a homeowner with a backyard, garage, or basement that could be converted, you're already in a good starting place. Homeowners looking to generate income through rental are among the most financially driven ADU construction clients, along with families supporting elderly parents.
Another strong candidate is someone who works from home and wants a detached creative or business space that remains away from your family's daily life. Real estate-minded homeowners who already own residential properties are also a natural fit for ADU construction, since rental income frequently offsets build costs.
Those who should discuss alternatives first include lots that are below minimum size here thresholds. Very small lots or properties with easements may need a modified approach. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction FAQ
How long does ADU construction generally take from start to finish?
The full timeline for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. City review on its own can take a significant portion of the overall timeline in San Jose, so starting early is important. Straightforward interior conversions can move faster, while multi-room detached cottages require more time.
What does ADU construction cost in San Jose?
Costs vary widely based on whether it's a conversion or new construction. For most projects in this region, ADU construction commonly costs $150,000 to $400,000 or more for a fully custom construction. Garage conversions tend to cost less, sometimes in the $80,000 to $150,000 range. An accurate budget can only be developed after a thorough property review.
Is ADU construction disruptive while it's underway?
How much the build affects daily life depends on where the ADU is being built. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Projects that connect to the main structure may involve some shared wall work during certain phases of construction. Brother & Brother Builders keeps you informed about any phases that may affect your routine.
Do I need to move out during ADU construction?
In most cases, you do not need to vacate your main home during ADU construction. The vast majority of projects are set up to let you remain on the property throughout the construction timeline. Exceptions may arise if significant structural connections require temporary shutoffs in ways that require short-term access disruption. Our construction supervisors will walk you through any potential disruptions during the pre-construction consultation.
How long will an ADU built through professional ADU construction hold up?
An ADU constructed with quality materials is designed to last as long as the main residence — typically 50 years or more. Durability depends to the standard of construction, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies commercial-grade materials and build to current California residential standards to ensure lasting performance.
ADU Construction for Local Homeowners
Residential areas across San Jose present a wide range of property types that are well suited for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties work well for both attached and detached projects. The Berryessa area have seen growing ADU activity as families expand. If you're located closer to Evergreen, our team has likely worked nearby.
San Jose's permitting office applies particular standards for ADU construction that require a builder familiar with local expectations. Proximity to transit corridors can impact the design approach for a given ADU project. Our team's knowledge of this region's building landscape means fewer surprises from design through the final walkthrough.
Book Your ADU Construction Assessment Today
If you're ready to explore what an ADU could look like on your lot, Brother & Brother Builders is here to help. Our experts offer licensed expertise in ADU construction across a wide range of project types — from modest studio builds to fully independent secondary homes. The process begins with a thorough and honest property review where we understand your vision and give you a realistic picture of what's achievable.
Contact Brother & Brother Builders to set up your consultation. No matter where you are in the decision-making process, we enjoy walk through your options, review completed projects and give you the clarity you need to move forward. Building an ADU is a major decision — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632