ADU · Orange County
Can you build an ADU in Cornwall-on-Hudson, NY?
Village of Cornwall-on-Hudson has 6 districts. 4 districts allow ADUs with occupancy restrictions, 2 do not. Check your address to confirm the district that applies to your parcel:
What the Cornwall-on-Hudson code says
In CR-1 and SR, an accessory apartment is allowed in an owner-occupied single-family detached house, but only if the house was lawfully built and used as a single-family detached dwelling for at least 10 years before the application (§ 172-48.3D).
Conditions the code attaches:
- The Planning Board may waive the 10 years only on a showing that the apartment will let the owner care for an elderly or disabled relative living in it.
- The apartment must have at least 450 square feet of habitable floor area and no more than 30% of the house's gross floor area or 750 square feet, whichever is less (§ 172-48.3C).
- A proposed unit larger than that maximum makes the building a two-family dwelling, a different use with its own district availability.
- The house must be the record owner's principal domicile at application and at all times after, shown by the last recorded deed and an owner affidavit (§ 172-48.3E).
- Separate ownership of the apartment, such as a condominium, is barred.
- The application goes to the Planning Board, with a scaled floor plan and a public hearing.
What the Cornwall-on-Hudson 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 |
|---|---|---|---|---|
| Conservation Residential (Scenic) | 3.67 ac | 100 / 40 / 60 ft | 35 ft | Occupancy restricted |
| Conservation Residential (Rural) | 1.84 ac | 50 / 40 / 60 ft | 35 ft | Occupancy restricted |
| Conservation Residential | 0.92 ac | 50 / 20 / 50 ft | 35 ft | Occupancy restricted |
| Suburban Residential | 0.34 ac | 30 / 15 / 30 ft | 35 ft | Occupancy restricted |
| Waterfront Recreation | — | — | 35 ft | No |
| Industrial | 0.92 ac | 40 / 20 / 20 ft | 45 ft | No |
Conservation Residential (Scenic) - Along both sides of Deer Hill Road a conservation green belt runs twenty-five feet back from the edge of the paved right-of-way, and no tree cutting, construction or other development is permitted in it except a driveway the Planning Board approves.
Conservation Residential (Rural) - Along the west side of the Boulevard, opposite the Village-owned parkland, the front yard is a hundred and fifty feet instead of the figure shown.
- That deeper front yard is a greenbelt setback in which no further construction, tree cutting or other development is permitted without specific action of the Planning Board.
ADUs vs. short-term rentals in Cornwall-on-Hudson
Short-term rentals allowed with local rules for Village of Cornwall-on-Hudson. Short-term rentals in the Village of Cornwall-on-Hudson are limited to owner-occupied dwellings and need a registration or permit under the Village's short-term rental chapter. 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 minimum0.34–3.67 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityCentral Hudson territory.
- Zoning codeecode360.com/15451507
- Building dept(845) 534-4200
ADU FAQ — Cornwall-on-Hudson, NY
Are ADUs allowed in Cornwall-on-Hudson, NY?
Village of Cornwall-on-Hudson has 6 districts. 4 districts allow ADUs with occupancy restrictions, 2 do not. Check your address with the free ADU checker, or confirm with the building department at (845) 534-4200.
Do I need a special permit for an ADU in Cornwall-on-Hudson?
No district in Village of Cornwall-on-Hudson requires a special-use permit for an ADU - 4 districts allow ADUs with occupancy restrictions, 2 do not. Site-plan review or a building permit may still apply.
Can I use an ADU as a short-term rental in Cornwall-on-Hudson?
Short-term rentals allowed with local rules for Village of Cornwall-on-Hudson. 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.
What an ADU costs to build in Cornwall-on-Hudson
Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $205k–270k 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 Cornwall-on-Hudson, priced by size.
How we know this
- Sections analyzed
- § 172-48.3 · § 172-70 · §§ 172-5.5, 172-6, 172-7, 172-8, 172-10, 172-11
- Districts confirmed
- 6 of 6 — every mapped district.
- Last reviewed
- 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 Cornwall-on-Hudson: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Orange County · All Orange County towns
ADU information for Village of Cornwall-on-Hudson is compiled from the municipal code (last reviewed 2026-07-12) 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) 534-4200 before relying on any answer. Source: the Offsite / Aldo zoning dataset.