ADU · Dutchess County

Can you build an ADU in Millbrook, NY?

Village of Millbrook has 8 districts. All districts allow ADUs with a special-use permit. Check your address to confirm the district that applies to your parcel:

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What the Millbrook code says

An accessory apartment needs a Planning Board special permit, and the owner must live in one of the units. In RMF and GB one inside the house is not permitted; a detached one may be, but the code conflicts on whether it needs the special permit, so confirm with the Village.

Conditions the code attaches:

One apartment only, with at most one bedroom, floor area over 400 sq ft and not more than 35% of the one-family house's floor area.
A detached apartment must convert a gatehouse, garage, barn or similar accessory structure, without enlargement unless it conforms to density, and not where the house already has one inside.
In BCD, whether a detached apartment is allowed is not confirmed.
Private water and sewage capacity must be adequate for two units, and the permit can be revoked if problems are not fixed.
The permit ends on a change of ownership or of the owner's residence; a new owner has 90 days to reapply, or the tenant gets 90 days to relocate and the kitchen must go within 60 days.
An accessory apartment may also be used as a short-term rental, which needs a special permit in all eight districts.

What the Millbrook 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
Rural	5 ac	75 / 50 / 50 ft	35 ft	Special permit
Residential Low-Density	2 ac	50 / 25 / 30 ft	35 ft	Special permit
Residential Transitional	1.5 ac	50 / 30 / 30 ft	35 ft	Special permit
Residential - One Acre	1 ac	35 / 20 / 30 ft	35 ft	Special permit
Residential	0.33 ac	25 / 10 / 30 ft	35 ft	Special permit
Multifamily Residential	0.23 ac	30 / 15 / 30 ft	35 ft	Special permit
Bennett Campus District	2 ac	50 / 30 / 30 ft	35 ft	Special permit
General Business	0.092 ac	10 / 0 / 15 ft	35 ft	Special permit

Rural, Residential Low-Density, Residential Transitional, Residential - One Acre, Residential, Multifamily Residential - Height is capped at 2 1/2 stories as well as 35 ft.

Lot depth is its own requirement: a lot can meet the area and the width and still fail on depth.

Bennett Campus District - Two-acre single-family zoning is as of right in BCD. A Conservation Density Development, a planned unit development inside BCD, is available only by special use permit.

Height is capped at 2 1/2 stories as well as 35 ft.
Lot depth is its own requirement: a lot can meet the area and the width and still fail on depth.

General Business - No side yard is required in General Business. Height is capped at 2 1/2 stories as well as 35 ft.

Lot depth is its own requirement: a lot can meet the area and the width and still fail on depth.

ADUs vs. short-term rentals in Millbrook

Short-term rentals allowed with local rules for Village of Millbrook. Short-term rentals are regulated as overnight accommodations under § 230-30 of the Village zoning, which defines hosted and nonhosted short-term rentals separately. Work out which form a property would be before relying on any answer, and confirm with the Village before listing. 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 minimum0.23–5 ac — an ADU still has to fit the district's lot and setback envelope.
UtilityCentral Hudson territory.
Zoning codeecode360.com/10855096
Building dept(845) 677-8419

ADU FAQ — Millbrook, NY

Are ADUs allowed in Millbrook, NY?

Village of Millbrook has 8 districts. All districts allow ADUs with a special-use permit. Check your address with the free ADU checker, or confirm with the building department at (845) 677-8419.

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

Yes. Every district in Village of Millbrook requires a special-use permit for an ADU rather than allowing one as of right. Check the conditions attached to it before you design.

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

Short-term rentals allowed with local rules for Village of Millbrook. 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 Millbrook

Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $210k–275k 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 Millbrook, priced by size.

How we know this

Sections analyzed: Ch. 230 Attachment 1 Schedule of Permitted Uses and Special Permit Uses (amended 2-14-2024 by L.L. No. 2-2024); § 230-27 Accessory apartments; § 230-12; § 230-6
Districts confirmed: 8 of 8 — 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 Millbrook: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Dutchess County · All Dutchess County towns

ADU information for Village of Millbrook 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 (845) 677-8419 before relying on any answer. Source: the Offsite / Aldo zoning dataset.