Unlock New Space with Expert ADU Construction
Property owners throughout San Jose, CA are realizing that adding an accessory dwelling unit is one of the smartest 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 craftsmanship and care.
The popularity of ADU construction has increased significantly 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 encouraged the trend as a way to expand the housing supply. Whether you're building a detached backyard cottage, a click here 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 build. Our team knows the San Jose building codes, the engineering considerations, and the aesthetic decisions that make an ADU functional. If you've been thinking about what ADU construction could look like on your property, this guide explains everything you need to know.
What Is the ADU Construction Process?
ADU construction describes the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a self-contained living space — equipped with a kitchen, bathroom, sleeping area, and its own entryway — that exists on the same lot as a primary residence. ADU construction includes various structural types, including detached backyard units, attached additions, garage conversions, and even basement or interior conversions.
Mechanically, the process begins with a detailed site assessment, where our team evaluate property boundaries, available square footage, and infrastructure capacity. 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 encompasses site preparation, framing, mechanical systems, weatherproofing, and interior finishing. The result is a fully functional living unit adjacent to or detached from your main home.
The difference between a good and a great ADU build is the depth of planning at every stage. Materials must be selected to align with the neighborhood's character. Systems like plumbing and electrical must be designed to handle full-time occupancy. Brother & Brother Builders approaches every build with the same professional rigor we bring to full custom home projects.
Key Reasons to Choose ADU Construction
- Boosted Home Equity — ADU construction adds measurable 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, generating steady monthly revenue for the homeowner.
- Multi-Generational Living — ADU construction gives aging parents a private, independent living space without losing proximity to the family.
- Personalized Layouts — From two-bedroom configurations, ADU construction is adaptable to your household's priorities.
- Faster Permitting in California — Recent state legislation has cut down the barriers and delays associated with ADU construction, creating a path that is faster and more affordable than ever before.
- Efficient Use of Your Lot — Building an ADU works within your current footprint instead of expanding urban sprawl, which aligns with sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction produces a fully self-contained unit where occupants have full privacy.
- Durable Return on Investment — A well-built ADU continues to produce returns for many years and generates both usable housing and equity growth.
The ADU Construction Procedure Step by Step
- Site Evaluation and Zoning Analysis — Our team visits your property to analyze zoning rules, slope conditions, and available square footage. This step tells you exactly what can be built before any resources go toward planning.
- Architectural Drafting and Space Planning — Experienced draftspeople create comprehensive blueprints reflecting your priorities. Space is thoughtfully allocated to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose requires submitting plans to the city's building department for inspection and clearance. Our team handles all submissions on your behalf, responding to review feedback promptly.
- Excavation and Foundation Installation — Once permits are granted, physical construction begins. This covers land preparation, 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. At this stage, the ADU transforms from a concept to a building.
- MEP Systems Rough-In — Licensed subcontractors install the heating, cooling, drainage, and power infrastructure that make the ADU fully functional. Inspections are completed at required milestones throughout ADU construction.
- Finishes, Fixtures, and Final Walkthrough — Countertops, hardware, finishes, and fixtures are installed and finished to the agreed design. A closing municipal review issues the certificate of occupancy and your new space is cleared for use.
Who Is a Right Fit for ADU Construction?
Property owners who are best suited 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 looking to generate income through rental are among the most financially driven ADU construction clients, along with families accommodating adult children who need housing.
You may also be someone who works from home and wants a separate office or studio 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 the long-term value is proven.
Those who should discuss alternatives first include properties with significant setback limitations. Parcels in historic districts or HOA-restricted communities may require additional review. Our experts will evaluate each property individually and honestly to provide realistic options.
ADU Construction Common Questions Answered
How long does ADU construction typically take from start to finish?
The total process for ADU construction usually runs between six to fourteen months, based on the project scope and local permitting timelines. The approval phase alone can take a significant portion of the overall timeline in San Jose, so beginning the process sooner rather than later is wise. Simpler garage conversions can move faster, while multi-room detached cottages require more time.
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 fully custom construction. Garage conversions often come in under, sometimes starting around $80,000 depending on scope. A detailed estimate can only be given after completing a formal feasibility evaluation.
Is ADU construction intrusive while it's underway?
The day-to-day impact depends on the project's location on your property. Detached backyard builds are usually easier to live alongside, since the construction zone is separate. Projects that connect to the main structure may require temporary access during certain phases of construction. Our team communicates clearly about any phases that may affect your routine.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. The vast majority of projects are set up to let you stay in your primary unit throughout the build. There are edge cases if major utility upgrades affect the main house in ways that briefly affect habitability. The team at Brother & Brother Builders will flag these situations during the kickoff meeting.
How long will an ADU built through professional ADU construction last?
A well-built ADU should last as long as the main residence — indefinitely with proper upkeep. Durability depends to the quality of materials used, how consistently minor repairs are addressed, and if mechanical components are maintained on schedule. Brother & Brother Builders specifies high-quality components and comply with all local building codes to deliver a structure that stands the test of time.
ADU Construction for San Jose Homeowners
The communities throughout San Jose provide a wide range of property types that are ideally positioned for ADU construction. Homeowners in the Willow Glen neighborhood often discover their properties accommodate detached backyard units nicely. Communities around the Capitol Expressway corridor have seen growing ADU activity as multigenerational living becomes more common. If you're located closer to Evergreen, our team has project experience in the area.
Local regulatory bodies in this area follows defined procedures for ADU construction that require a builder familiar with local expectations. Location near major arterials like Story Road or Tully Road can influence utility connection requirements for a given ADU project. Our familiarity with this region's building landscape means fewer surprises from kickoff through certificate of occupancy.
Schedule Your ADU Construction Assessment Today
If you're ready to add an ADU to your property, Brother & Brother Builders is ready to guide you. Our experts offer years of hands-on experience in ADU construction including all types of project types — from small attached additions to fully independent secondary homes. Our approach opens 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 begin the conversation. Whether you're in the early stages of planning, we're glad to 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