Case Study: When the 'Simple' ADU Option Wasn't
Grace was exploring the idea of building an Accessory Dwelling Unit (ADU) on their property — a place for aging parents that would allow them to stay close while maintaining some independence. Between prefab ADU manufacturers and modular home coverage in the press, the project seemed straightforward. The client came to us mid-renovation on their main house, looking for guidance on how to layer in the ADU without derailing what was already underway.
Using PermitWut!™, we quickly reframed the timeline. Despite the availability of quality modular options, permitting a standalone structure on the property can take several months in New York — and that clock starts before a single shovel hits the ground.
The more significant complication was what the ADU would trigger downstream. The property relied on a private septic system, and adding bedrooms would require a formal septic review. Depending on the outcome, that could mean replacing the existing system with a higher-capacity one — a costly and disruptive undertaking that would also affect permitting for the main house renovation already in progress. Add to that the foundation work, plus running plumbing and electrical to a detached structure, and the all-in cost of a "simple" prefab ADU looked considerably different than the sticker price suggested.
With that full picture in hand, we proposed an alternative: convert the existing unfinished attached garage into a self-contained living space — separate entrance, private bathroom, and kitchenette. Functionally, it would serve the same purpose as the ADU. Practically, it was far simpler: lower cost, faster to permit, and designed to integrate with the main house renovation rather than compete with it.
"I was already in the middle of a renovation when I started thinking about the ADU. The last thing I needed was to make a decision that would derail everything already underway. design + biz mapped out the full picture before I committed to anything — and steered me toward a solution that was faster, cheaper, and actually worked with the project I already had in progress."
— Grace, New York
