ADU · Ulster County

Can you build an ADU in Marlborough, NY?

Town of Marlborough has 7 districts. All districts prohibit ADUs. Check your address to confirm the district that applies to your parcel:

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What the Marlborough code says

Marlborough's code has no accessory dwelling use at all, and § 155-11A closes every district's use list to uses it does not name. A two-family residence is the second-unit route, a principal permitted use by right in the town's residential districts.

Conditions the code attaches:

Outside the C and C2 districts, § 155-12.2A limits residential use of a lot to one single-family residence, or one two-family residence if density allows.
A two-family residence is also subject to the septic sizing rules in § 155-13.

What the Marlborough 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
R Residential	0.46 ac	10 / 10 / 20 ft	35 ft	No
R-1 Residential	1 ac	35 / 35 / 50 ft	35 ft	No
R-Ag-1 Rural Agricultural	1 ac	50 / 35 / 75 ft	35 ft	No
C-1 Hamlet Commercial	0.34 ac	5 / 0 / 20 ft	35 ft	No
C-2 Highway Commercial	0.46 ac	35 / 35 / 30 ft	35 ft	No
HD Harbor Development	2 ac	75 / 25 / 75 ft	45 ft	No
I Industrial	5 ac	75 / 25 / 75 ft	35 ft	No

R Residential - The minimum lot drops to 15,000 sq ft with public water or public sewer, 10,000 sq ft with both, and 7,500 sq ft where the lot has public water, public sewer and natural gas.

R-1 Residential, R-Ag-1 Rural Agricultural - The minimum lot size is set by the percolation tests required under § 155-42, and in no event less than one acre.

Where the lot adjoins active agricultural land, § 155-52 requires a 75 ft setback from the property line, and that setback replaces the figures shown here.

C-1 Hamlet Commercial - The minimum lot drops to 10,000 sq ft with public water or public sewer and 5,000 sq ft with both. No side yard is required in this district, and none is required even where one is provided.

C-2 Highway Commercial - The 20,000 sq ft minimum lot size is the figure for a lot without public water or sewer, and the code publishes no smaller figure where either utility is available.

HD Harbor Development - The minimum lot drops to 1.5 acres with public water and sewer. Where the lot adjoins active agricultural land, § 155-52 requires a 75 ft setback from that property line, which supersedes the yards shown.

Height is four stories as well as 45 ft, and where the two measures disagree the lesser applies.
A building over 35 ft requires a visual impact analysis under SEQRA because the district lies within the Coastal Boundary Zone.

ADUs vs. short-term rentals in Marlborough

Short-term rentals allowed with registration for Town of Marlborough. A short-term rental permit is required in the Town of Marlborough. 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. Municipal source

Good to know

Residential lot minimum0.46–1 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityCentral Hudson territory.
Zoning codeecode360.com/MA0587
Building dept(845) 236-7600

ADU FAQ — Marlborough, NY

Are ADUs allowed in Marlborough, NY?

Town of Marlborough has 7 districts. All districts prohibit ADUs. Check your address with the free ADU checker, or confirm with the building department at (845) 236-7600.

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

No. No district in Town of Marlborough permits an ADU, so there is no permit to apply for. Codes change, so verify with the building department at (845) 236-7600 before ruling it out.

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

Short-term rentals allowed with registration for Town of Marlborough. 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.

Run the free ADU check for your parcel →

What an ADU costs to build in Marlborough

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $200k–265k 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 Marlborough, priced by size.

How we know this

Zoning code: ecode360.com/MA0587
Districts confirmed: 7 of 7 — every mapped district.
Last reviewed: Apr 2026
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 Marlborough: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Ulster County · All Ulster County towns

ADU information for Town of Marlborough is compiled from the municipal code (last reviewed Apr 2026) 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 (845) 236-7600 before relying on any answer. Source: the Offsite / Aldo zoning dataset.