Transform Your Property with Quality ADU Construction
Homeowners across San Jose, CA are realizing that adding an accessory dwelling unit is one of the most rewarding investments they can make. ADU construction creates a flexible new living space on your existing property — whether you want to create a private workspace. Brother & Brother Builders has supported hundreds of local homeowners bring these projects to life with craftsmanship and transparency.
The popularity of ADU construction has surged in recent years, and it's not hard to see why. California state law has streamlined permitting for homeowners to build these secondary units, and local municipalities like San Jose have supported the trend as a way to increase density responsibly. 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 bring years of hands-on experience to every ADU construction job. Our team is familiar with city and county requirements, the engineering details, and the planning steps that make an ADU functional. If you've been thinking about what ADU construction could do for your property, this guide covers everything you need to know.
What Is ADU Construction?
ADU construction refers to the process of engineering, filing for, and completing an accessory dwelling unit on a residential property. An accessory dwelling unit is a complete living space — equipped with a kitchen, bathroom, sleeping area, and its own access point — that sits on the same property 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 team evaluate lot dimensions, existing structures, soil conditions, and local code requirements. From there, blueprints are prepared and submitted to the local website building department. Once approvals are in place, ADU construction transitions to the physical build phase — which includes foundation work, framing, roofing, plumbing, electrical, insulation. The result is a move-in-ready living unit adjacent to or detached from your main home.
What separates excellent ADU construction from an average project is the depth of planning at every stage. Materials must be selected to match the primary home's aesthetic. Systems like wiring and water supply must be sized for independent daily use. Brother & Brother Builders handles every ADU construction job with the same professional rigor we use on major 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.
- Rental Income Potential — A completed ADU may be listed as a long-term rental or short-term vacation unit, generating steady monthly revenue for the homeowner.
- Housing for Extended Family — ADU construction gives aging parents a comfortable home of their own without leaving the property.
- Customization Options — From modern studio layouts, ADU construction can be tailored to the intended occupant's lifestyle.
- Streamlined Approval Process — Recent state legislation has reduced the red tape 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 consuming open land, which supports broader sustainability goals.
- Separate Entrances and Spaces — Unlike a bedroom addition, ADU construction creates a truly separate unit where tenants live autonomously.
- Durable Return on Investment — A well-built ADU remains an asset for the long haul by offering both usable housing and equity growth.
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 phase answers exactly what can be built before any money is spent on design.
- Blueprint Development and Layout Design — Experienced draftspeople create detailed floor plans based on your goals. Space is thoughtfully allocated to optimize daily use.
- Permitting and City Approval — ADU construction in San Jose involves filing drawings to the city's building department for review and approval. Brother & Brother Builders coordinates the permitting on your behalf, responding to review feedback promptly.
- Ground Prep and Structural Base — Once permits are issued, on-site work kicks off. This involves leveling and prepping the ground, laying the structural base, and establishing utility connections.
- 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.
- Mechanical, Electrical, and Plumbing Installation — Certified technicians install the plumbing lines, electrical wiring, and HVAC systems that make the ADU fully functional. Every system is reviewed at each code checkpoint throughout ADU construction.
- Interior Finishing and Final Inspections — Flooring, cabinetry, fixtures, paint are fitted and completed to the agreed design. A closing municipal review confirms the unit is code-compliant and the unit is officially approved for use.
Who Is a Strong Candidate for ADU Construction?
People who see the greatest return from ADU construction generally fit within 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 wanting to add a revenue stream through rental are among the most motivated ADU construction clients, along with families supporting elderly parents.
You may also be someone who needs a dedicated professional workspace and wants a private work environment that is distinct from your family's daily life. Real estate-minded homeowners who already own residential properties are also well suited 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 need a modified approach. Our experts will evaluate each property case by case to advise you on what's feasible.
ADU Construction FAQ
How long does ADU construction usually 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. City review on its own can take two to four months in San Jose, so planning ahead matters. Simpler garage conversions 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 fully custom construction. Attached ADU additions tend to cost less, sometimes in the $80,000 to $150,000 range. A precise cost projection can only be given after completing a full site assessment.
Is ADU construction disruptive while it's underway?
The level of disruption depends on whether you're converting existing space or building new. Detached backyard builds are typically less disruptive, since work happens away from the main house. Projects that connect to the main structure may create short-term inconveniences during key milestones. Our team communicates clearly about what to expect at each stage.
Do I need to vacate the property during ADU construction?
Generally speaking, you won't have to vacate your main home during ADU construction. Most job sites are set up to let you continue living in the home throughout the construction timeline. There are edge cases if major utility upgrades affect the main house in ways that require short-term access disruption. Our project managers will flag these situations during the pre-construction consultation.
How long will an ADU built through professional ADU construction last?
A well-built ADU is designed to last as long as the main residence — indefinitely with proper upkeep. Longevity is tied to the quality of materials used, how consistently minor repairs are addressed, and how proactively issues are resolved over time. We select 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
Residential areas across San Jose present a variety of property types that are well suited for ADU construction. Property owners near the Almaden Valley area have found their lots accommodate detached backyard units nicely. Neighborhoods near Blossom Hill Road have seen growing ADU activity as housing demand rises. If you're located closer to Evergreen, our team has project experience in the area.
San Jose's permitting office applies particular standards for ADU construction that experienced builders know well. Access to infrastructure along thoroughfares like Monterey Road can affect how quickly permits are approved for a given ADU project. Our familiarity with these local conditions means smoother project delivery from kickoff through certificate of occupancy.
Start Your ADU Construction Assessment Today
Should you be thinking about how to explore what an ADU could look like on your lot, Brother & Brother Builders is ready to guide you. We bring proven skills in ADU construction across a wide range of project types — from simple garage conversions to fully independent secondary homes. Our approach opens with a detailed, no-pressure consultation where we listen to your goals 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 answer questions, share examples of our work and give you the clarity you need to move forward. This type of project is a meaningful commitment — and our goal is to ensure it delivers real value.
Brother & Brother Builders | 3109 Stevens Creek Boulevard | San Jose CA 95117 | (888) 412-2632