Expand Your Home with Professional ADU Construction
Homeowners across San Jose, CA are finding that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction opens the door to a powerful new living space on your existing property — whether you want to generate rental income. Brother & Brother Builders has helped hundreds of local homeowners turn these plans to life with skill and transparency.
The interest in ADU construction has surged in recent years, and it's easy to understand why. California state law now makes it easier for homeowners to build these secondary units, and local municipalities like San Jose have embraced the trend as a way to increase density responsibly. Whether you're building 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 project. Our team knows the San Jose building codes, the engineering details, and the design choices that make an ADU beautiful. When you're ready to explore what ADU construction could mean for your property, this guide will walk you through everything you need to know.
What Is ADU Construction?
ADU construction describes the process of planning, approving, and constructing an accessory dwelling unit on a residential property. An accessory dwelling unit is a fully independent living space — featuring a kitchen, bathroom, sleeping area, and its own entrance — 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 detailed site assessment, where our professionals evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, architectural drawings are prepared and submitted to the local building department. Once the paperwork is cleared, ADU construction enters the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a completely finished 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. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be designed to handle full-time occupancy. Brother & Brother Builders handles every ADU construction job with the same professional rigor we apply to large-scale custom home projects.
Key Reasons to Choose ADU Construction
- Higher Resale Potential — ADU construction adds measurable market value to your property, often returning more than the build cost when it's time to sell.
- Monthly Cash Flow — A completed ADU can be rented 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 private, independent living space without leaving the property.
- Personalized Layouts — From modern studio layouts, ADU construction is adaptable to your specific needs.
- Simplified Regulatory Path — Recent state legislation has reduced the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Sustainable Land Use — Building an ADU maximizes the land you already own instead of requiring new development, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where residents have their own space.
- Durable Return on Investment — A well-built ADU remains an asset for many years and generates both livable square footage and monetary benefit.
The ADU Construction Process Step by Step
- Initial Property Assessment and Feasibility Review — Our team visits your property to determine what type of ADU is allowed and where it can be placed. This step tells you exactly what can be built before any resources go toward planning.
- Blueprint Development and Layout Design — Licensed architects and designers create comprehensive blueprints based on your goals. Every square foot is planned to maximize function and livability.
- Permit Submission and Municipal Review — ADU construction in San Jose demands documentation to the city's building department for inspection and clearance. Brother & Brother Builders coordinates the permitting on your behalf, resolving any revision requests promptly.
- Site Preparation and Foundation Work — Once permits are approved, the build starts. This includes grading the site, completing foundation work, and establishing utility connections.
- Shell Construction and Exterior Finishing — The structural frame is erected followed by roofing, siding, windows, and exterior doors. This phase, the ADU becomes recognizable as a structure.
- MEP Systems Rough-In — Licensed subcontractors install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at required milestones throughout ADU construction.
- Interior Completion and City Sign-Off — Trim, appliances, tile, and lighting are fitted and completed to the approved plan. A closing municipal review confirms the unit is code-compliant and your new space is cleared for use.
Who Is a Strong Candidate for ADU Construction?
Property owners who are best suited from ADU construction often belong to a few clear categories. If you have a residential property 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 motivated ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who runs a small business and wants a detached creative or business space that doesn't interfere with your family's daily life. Property investors and rental owners who are building a portfolio are also well suited for ADU construction, since rental income frequently offsets build costs.
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 need a modified approach. Brother & Brother Builders reviews each property on its own merits to provide realistic options.
ADU Construction Frequently Asked Questions
How long does ADU construction generally take from start to finish?
The complete duration for ADU construction usually runs between six to fourteen months, depending on design complexity and click here how quickly approvals come through. Permitting alone can take two to four months in San Jose, so planning ahead matters. Smaller detached units can move faster, while custom detached builds fall toward the upper end of the timeline.
What does ADU construction typically cost?
Pricing depends on many factors based on the type and size of the ADU. For most projects in this region, ADU construction typically ranges from $150,000 to $400,000 or more for a standalone backyard unit. Attached ADU additions are generally priced lower, sometimes in the $80,000 to $150,000 range. An accurate budget can only be given after completing a thorough property review.
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 usually easier to live alongside, since the construction zone is separate. Interior conversions may create short-term inconveniences during certain phases of construction. We provide advance notice about any phases that may affect your routine.
Do I need to leave my home during ADU construction?
For the majority of homeowners, you do not need to vacate your house during ADU construction. Most job sites are set up to let you stay in your primary unit throughout the build. Certain situations could require a brief departure if major utility upgrades affect the main house in ways that temporarily impact livability. The team at Brother & Brother Builders will discuss these scenarios during the kickoff meeting.
How long will an ADU built through professional ADU construction remain in good condition?
An ADU constructed with quality materials can be expected to last as long as your primary home — typically 50 years or more. Durability depends to the quality of materials used, whether the unit is properly cared for, and if mechanical components are maintained on schedule. Our builds use high-quality components and follow all code requirements to protect your investment for the long haul.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a diverse mix of property types that are ideally positioned for ADU construction. Property owners near the Almaden Valley area have found their lots accommodate detached backyard units nicely. The Berryessa area are increasingly popular for ADU construction as housing demand rises. Whether your property is near downtown San Jose, our team has likely worked nearby.
The City of San Jose's building department follows defined procedures for ADU construction that require a builder familiar with local expectations. Access to infrastructure along thoroughfares like Monterey Road can impact the design approach for a given ADU project. Brother & Brother Builders' experience across this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Consultation Today
When you want to move forward with ADU construction, Brother & Brother Builders is here to help. We bring licensed expertise in ADU construction across a wide range of project types — from small attached additions to large custom detached cottages. Every project starts with a detailed, no-pressure consultation where we learn what you're trying to accomplish and provide an honest assessment of what ADU construction on your property will look like.
Contact Brother & Brother Builders to schedule a site visit. Whether you're in the early stages of planning, we're glad to answer questions, share examples of our work 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