Chatham, NY ADU Rules: By-Right Approval Up to 1,200 Sq Ft

By Spenser McCoy

If you're comparing Hudson Valley towns for an ADU project, start with Chatham. In March 2025, the Town adopted one of the most straightforward accessory dwelling unit laws in the region — and it's worth understanding exactly why it's different.

Most Hudson Valley towns make you go through a special use permit, a Planning Board hearing, or both. Chatham doesn't. As long as your project meets the standard — up to 1,200 square feet, attached or detached, on any lot with a lawfully existing single-family, two-family, or multifamily use — it's approved by right with a building permit. No hearing. No board review, unless the property would end up with more than two total dwelling units, in which case Planning Board site plan review kicks in. The permit fee itself is even cut in half for ADUs.

There's no owner-occupancy requirement, which is genuinely rare for this region — most surrounding towns require you or a family member to live on-site. Chatham doesn't ask that. The one real restriction: you can't put the unit in the front yard, and you can't use it as a short-term rental for the first 10 years after approval. The unit also needs its own fully independent kitchen, bathroom, and living space — this isn't a mother-in-law suite that shares a bathroom with the main house.

The bottom line: Chatham is built for speed and flexibility. If your goal is getting from idea to permit with the least friction, this is one of the strongest codes in Columbia County.

FAQ Do I need a special permit for an ADU in Chatham? No — it's approved by right with a standard building permit in most cases.

Do I have to live on the property? No, Chatham has no owner-occupancy requirement. Can I rent my Chatham ADU short-term? Not for the first 10 years after approval.

Want to know exactly what your Chatham property qualifies for? Book a free Discovery Call with OneBuild today! We'll confirm the details and get your project moving.