The idea sounds straightforward: add a small secondary unit to your property - a basement apartment, a detached garage conversion, a backyard cottage - and unlock a rental income stream, house an aging parent, or create space for an adult child returning home. Accessory dwelling units, or ADUs, are one of the most practical and financially productive investments a CNY homeowner can make right now.

The reality on the ground, however, is considerably more complicated than the idea. Onondaga County is not a single jurisdiction - it is a patchwork of cities, towns, and villages, each governed by its own zoning ordinance, each with its own ADU policies, setback requirements, and approval timelines. What is permitted by right in one municipality can require a full variance hearing in the town next door.

This guide is a practical primer for any CNY homeowner who is seriously considering an ADU. It will walk you through the zoning landscape, the most common permit pitfalls, realistic timelines, and why working with a team that already knows your local code dramatically increases your odds of a smooth approval.