ADU · Columbia County

Can you build an ADU in Chatham, NY?

Town of Chatham has 7 districts. 6 districts allow ADUs, 1 does not. Check your address to confirm the district that applies to your parcel:

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What the Chatham code says

An accessory dwelling unit of up to 1,200 sq ft, attached or detached, is permitted by right in H-1, H-2, RL-1, RL-2, RL-3 and B, with no owner-occupancy requirement. It may not be used as a short-term rental for 10 years from approval.

Conditions the code attaches:

It is also permitted by right on any property with a lawfully preexisting single-family, two-family or multifamily use, or two single-family uses on one lot.
After 10 years from approval the unit may be subdivided onto its own lot, only if the structure and new lot meet the code without a variance and it has its own well, septic and electric.
One ADU per property. It may not sit within the front yard setback, and it is prohibited on child parcels created under § 170-28 Single Lot Exemptions.
It needs its own kitchen, bathroom, sleeping and living area and separate access, and must meet state and county building and fire codes, including water and sewer capability.
A unit built wholly within a conforming accessory structure that lawfully existed when the section was adopted is exempt from setback and height restrictions.
Off-street parking is required under § 180-30, and the building permit fee is reduced by 50%.

What the Chatham code indicates by district

The table below shows how each district treats ADUs, alongside the lot and setback standards that govern a second unit. District boundaries and conditions vary, so treat this as a starting point and confirm the district that applies to your parcel.

District	Min lot	Setbacks F / S / R	Max height	ADU
Hamlet One	1.5 ac	25 / 25 / 25 ft	35 ft	As of right
Hamlet Two	1.5 ac	25 / 25 / 25 ft	35 ft	As of right
Rural Lands One	10 ac	50 / 50 / 50 ft	35 ft	As of right
Rural Lands Two	5 ac	50 / 50 / 50 ft	35 ft	As of right
Rural Lands Three	3 ac	50 / 50 / 50 ft	35 ft	As of right
Business	2 ac	25 / - / 50 ft	35 ft	As of right
Industrial	2 ac	25 / 50 / 50 ft	35 ft	No

Hamlet One, Hamlet Two, Rural Lands Three, Business, Industrial - On a town road the required setback is the front yard shown plus 25 ft.

A lot abutting more than one street must provide the required frontage along every street (§ 180-8A).
The 35 ft height, measured above average ground level, does not apply to farming purposes, and the Board of Appeals may grant a variance where not disruptive or hazardous (§ 180-26).
Overhangs, cornices and bay windows may project 2 ft 6 in into a minimum yard, and roofless porches, roofless balconies and entrance steps, over a width of at most 16 ft, may project 5 ft (§ 180-8B).
Fences up to 6 ft are excluded from side and rear yards and may project 4 ft into the front yard (§ 180-8B).

Rural Lands One, Rural Lands Two - On a town road the required setback is the front yard shown plus 25 ft.

A lot of record at adoption whose area is a multiple of the minimum plus three or more acres may be divided so one lot only falls below it, never below 3 acres, with subdivision approval.
A lot abutting more than one street must provide the required frontage along every street (§ 180-8A).
The 35 ft height, measured above average ground level, does not apply to farming purposes, and the Board of Appeals may grant a variance where not disruptive or hazardous (§ 180-26).
Overhangs, cornices and bay windows may project 2 ft 6 in into a minimum yard, and roofless porches, roofless balconies and entrance steps, over a width of at most 16 ft, may project 5 ft (§ 180-8B).
Fences up to 6 ft are excluded from side and rear yards and may project 4 ft into the front yard (§ 180-8B).

ADUs vs. short-term rentals in Chatham

Short-term rentals allowed with local rules for Town of Chatham. Short-term rentals in the Town of Chatham need an annual permit from the Code Enforcement Officer, and each property owner is limited to one permit. These are separate questions from whether you can build an ADU — a unit you're allowed to add isn't automatically one you're allowed to rent nightly, so check both.

Good to know

Residential lot minimum1.5–10 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityNYSEG territory.
Zoning codeecode360.com/10484787
Building dept(518) 392-1651

ADU FAQ — Chatham, NY

Are ADUs allowed in Chatham, NY?

Town of Chatham has 7 districts. 6 districts allow ADUs, 1 does not. Check your address with the free ADU checker, or confirm with the building department at (518) 392-1651.

Do I need a special permit for an ADU in Chatham?

No district in Town of Chatham requires a special-use permit for an ADU - 6 districts allow ADUs, 1 does not. Site-plan review or a building permit may still apply.

Can I use an ADU as a short-term rental in Chatham?

Short-term rentals allowed with local rules for Town of Chatham. ADU occupancy and short-term-rental rules are separate: an ADU you can build isn't automatically one you can rent nightly. Confirm both before you count on STR income.

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What an ADU costs to build in Chatham

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $195k–260k at a standard finish, and the per-square-foot rate comes in above a full house because the kitchen, bath, panel and heating plant cost the same either way. See the full cost to build an ADU in Chatham, priced by size.

How we know this

Sections analyzed: Ch. 180 Zoning: Art III §§ 180-9 to 180-16.1 (district objectives and the H-1, H-2, RL-1, RL-2, RL-3, B and I tables); Art IV § 180-17 Site plan review, § 180-23.3 Accessory dwelling units (added 3-20-2025 by L.L. No. 3-2025) A, B(1)-(2), C(1), D(1)-(8), E(1)-(9), F(1); Art V § 180-26 height, § 180-30 parking; Ch. 170 § 170-28 Single Lot Exemptions
Districts confirmed: 7 of 7 — every mapped district.
Last reviewed: 2026-08-16
Not covered here: Overlay districts, the zoning map, and any conditions attached to an individual parcel. Size limits and owner-occupancy terms sit in the code section above, not in this summary.

More on Chatham: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Columbia County · All Columbia County towns

ADU information for Town of Chatham is compiled from the municipal code (last reviewed 2026-08-16) and provided for decision-support only — not legal or architectural advice. ADU eligibility, size, owner-occupancy and permit conditions vary by district and often carry exceptions; verify with the building department at (518) 392-1651 before relying on any answer. Source: the Offsite / Aldo zoning dataset.