Inspiration
As a California homeowner, I watched friends struggle to navigate ADU construction—confusing zoning laws, opaque cost estimates, and fragmented contractor info left them overwhelmed. I wanted to create a tool that demystified the process, putting clarity and control back into homeowners’ hands.
What it does
ADU Planner guides users from address-based eligibility checks to rental income projections. It breaks down ADU design options, compares contractor quotes, outlines financing paths, and calculates ROI—all in one intuitive web platform tailored for California homeowners.
How we built it
We started with mapping core user workflows (eligibility → design → finance → ROI) and translating California’s ADU regulations into actionable logic. We built the frontend with React for dynamic UI, paired with Node.js/Express for backend calculations, and used PostgreSQL to store location and cost data. AWS hosted the platform for scalability.
Challenges we ran into
Translating complex zoning regulations into user-friendly logic was tough—balancing accuracy with simplicity took dozens of iterations. We also struggled to align financial formulas (e.g., payback period = total cost ÷ net annual profit) with real-world variables like local rent rates.
Accomplishments that we're proud of
We created a seamless end-to-end workflow that turns overwhelming ADU planning into a step-by-step process. Users can go from entering their address to viewing a full ROI projection in minutes—no prior construction knowledge needed.
What we learned
We deepened our understanding of California’s ADU policy landscape and financial modeling for real estate. We also learned that user-centric design means prioritizing clarity over technical accuracy—simplifying complex rules without losing critical details.
What's next for this project
We plan to expand to other U.S. states (starting with Oregon and Washington) by adapting zoning logic to regional laws. We’ll add a visual 3D design tool for ADUs and integrate local contractor verification to connect users with vetted professionals. Finally, we’ll roll out a mobile-responsive version for on-the-go planning.
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