ADU · Westchester County
Can you build an ADU in Cortlandt, NY?
Town of Cortlandt has 21 districts. 12 districts allow ADUs with occupancy restrictions, 4 do not. 5 districts have incomplete data - verify with the building department at (914) 734-1010. Check your address to confirm the district that applies to your parcel:
What the Cortlandt code says
In CROS, R-160, R-80, R-40, R-40A, R-20, R-15, R-10, R-G, CC, HC and HC/9A an attached ADU is permitted and a detached one needs a Planning Board special permit; either way the owner must live in one of the units (§ 307-45C(2)).
Conditions the code attaches:
- A covenant filed with the County Clerk ends the permit on the owner's death, on transfer of title or when the owner stops occupying the lot; a new owner must apply for a new operating permit.
- One ADU per lot and no more than two dwelling units on the lot; the ADU is capped at 800 sq ft or 40% of the existing house, whichever is less, with at most two bedrooms.
- Short-term rental of either unit is prohibited, as is renting individual bedrooms in either unit.
- Every ADU needs a building permit, and one receiving a certificate of occupancy after August 1, 2025 also needs an operating permit renewed every three years or on a change of ownership.
- A detached ADU must meet the house's side and rear setbacks, may not sit in a required front or street-facing corner side yard, and may not be taller than the house.
- ADUs are not permitted in PROS, CD, MD or M-1, and the rule in PVD, COND M-1 and CAMP SMITH REUSE B is not confirmed.
What the Cortlandt 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 |
|---|---|---|---|---|
| Single-Family Residential District | — | — | — | Occupancy restricted |
| Single-Family Residential District | 1.84 ac | 50 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Single-Family Residential District | 0.92 ac | 50 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Single-Family and Two-Family Residential District | 0.92 ac | 50 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Single-Family Residential District | 0.23 ac | 25 / 6 / 20 ft | 35 ft | Occupancy restricted |
| Single-Family Residential District | 0.34 ac | 30 / 10 / 25 ft | 35 ft | Occupancy restricted |
| Single-Family Residential District | 0.46 ac | 35 / 15 / 30 ft | 35 ft | Occupancy restricted |
| General Residential District | 0.17 ac | 25 / 6 / 20 ft | 40 ft | Occupancy restricted |
| Planned Village Development | — | — | — | — |
| Designed Industrial District | 5 ac | 75 / 75 / 75 ft | 40 ft | No |
| Community Commercial District | 0.34 ac | 30 / 10 / 10 ft | 35 ft | Occupancy restricted |
| Designed Commercial District | 1.84 ac | 75 / 50 / 50 ft | 35 ft | No |
| Conditional M-1 | — | — | — | — |
| Highway Commercial District | 0.46 ac | 30 / 30 / 30 ft | 35 ft | Occupancy restricted |
| HC-9A District | 0.46 ac | 30 / 30 / 30 ft | 35 ft | Occupancy restricted |
| Light Industrial District | 0.46 ac | 40 / 20 / 30 ft | 40 ft | No |
| Camp Smith Reuse District B | — | — | 40 ft | — |
| Conservation, Recreation and Open Space District | 15 ac | 50 / 50 / 30 ft | 35 ft | Occupancy restricted |
| Parks, Recreation and Open Space District | — | — | — | No |
| Annsville Waterfront Enhancement District | 0.17 ac | 10 / 10 / 10 ft | 35 ft | — |
| M-1A District | — | — | — | — |
Single-Family Residential District - Chapter 307 publishes no dimensional figures for R-160.
- A two-family home in a transitional location needs a special permit and takes the R-G two-family standards: at least 10,000 sq ft, 70 ft of width and at most 45 percent building coverage (§ 307-48).
- The front yard may be reduced to the average of the improved lots where at least half the lots on the same side of the street within 500 feet already hold single or two-family homes (§ 307-18A).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- A building owned and occupied by a government agency or a public school may reach 75 feet if every yard is widened one foot for each extra foot of height (§ 307-18F).
- The Town Board may authorize a cluster subdivision, which may hold no more homes than a conventional layout would (§ 307-19).
Single-Family Residential District, Single-Family Residential District, Single-Family Residential District - A two-family dwelling is a special permit use, and only in a transitional location; it then takes the R-G two-family standards: at least 70 ft of width, 25 ft of front yard, 6 ft on one side and 20 ft of rear yard, up to 40 ft of height and 45 percent building coverage.
- A transitional location is a lot whose side line runs along a commercial or industrial district for at least half its length, or whose front line faces one across the street for over half of it.
- The front yard may be reduced to the average of the improved lots where at least half the lots on the same side of the street within 500 feet already hold single or two-family homes (§ 307-18A).
- A Town Board cluster subdivision may hold no more homes than a conventional layout would, and its setback from the boundary of the tract is the district's own figure for one-family homes (§ 307-19).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An accessory building may not stand in a front yard, is limited to 17 feet in height and needs 6 feet to the side and rear lines; one holding an accessory dwelling unit owes the main building's yards.
- A flag lot needs at least 50 feet of frontage, and the access strip does not count toward lot area (§ 307-18I).
Single-Family and Two-Family Residential District - An existing lot in two-family use needs at least 20,000 square feet and 100 feet of width and 15 feet of side yard, and may cover 30 percent of the lot; a new lot laid out for a two-family home meets the standard lot figures.
- The front yard, the rear yard and the height are the same either way.
- A two-family dwelling in a transitional location is a separate special permit route under § 307-48 and takes the R-G two-family standards.
- The front yard may be reduced to the average of the improved lots where at least half the lots on the same side of the street within 500 feet already hold single or two-family homes (§ 307-18A).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An accessory building may not stand in a front yard, is limited to 17 feet in height and needs 6 feet to the side and rear lines; one holding an accessory dwelling unit owes the main building's yards.
- All accessory structures together may not cover more than the main building's footprint, and no single one may exceed 70 percent of it.
Single-Family Residential District, Single-Family Residential District - A two-family dwelling is a special permit use, and only in a transitional location; it then takes the R-G two-family standards: at least 70 ft of width, 25 ft of front yard, 6 ft on one side and 20 ft of rear yard, up to 40 ft of height and 45 percent building coverage.
- A transitional location is a lot whose side line runs along a commercial or industrial district for at least half its length, or whose front line faces one across the street for over half of it.
- The front yard may be reduced to the average of the improved lots where at least half the lots on the same side of the street within 500 feet already hold single or two-family homes (§ 307-18A).
- A Town Board cluster subdivision may hold no more homes than a conventional layout would, and its setback from the boundary of the tract is the district's own figure for one-family homes (§ 307-19).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An accessory building may not stand in a front yard, may not be over 17 ft tall, and needs 6 ft to the side line and 10 ft to the rear; one holding an accessory dwelling unit owes the house's yards.
- A flag lot needs at least 50 feet of frontage, and the access strip does not count toward lot area (§ 307-18I).
General Residential District - A two-family dwelling needs at least 10,000 square feet of lot and 70 feet of width and may cover 45 percent of the lot; the yards and the height are the same either way.
- A two-family dwelling built or converted before November 9, 1993 is permitted outright; a new one needs a special permit (§ 307-64).
- There is no 12-foot limit on the height of a single story here.
- The front yard may be reduced to the average of the improved lots where at least half the lots on the same side of the street within 500 feet already hold single or two-family homes (§ 307-18A).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An accessory building may not stand in a front yard, is limited to 17 feet in height and needs 6 feet to the side and rear lines; one holding an accessory dwelling unit owes the main building's yards.
- All accessory structures together may not cover more than the main building's footprint, and no single one may exceed 70 percent of it.
Planned Village Development - The lot and yard standards for PVD are not confirmed. Confirm them with the Town of Cortlandt Department of Technical Services before planning a building.
Designed Industrial District - At least 40 percent of the lot area must be landscaped, which is a minimum planting requirement and not a cap on paving, and the landscaping separating buildings, parking and driveways from the street must be a continuous strip 25 feet wide (§ 307-21B(2)).
- The height limit is stated as 3 stories or 40 feet, whichever is less.
- A contractor's yard or a specialty trade contractor is a special permit use whose own standards cap impervious coverage, including the buildings, at 55 percent of the site (§§ 307-65.5 and 307-65.6).
- Outdoor light fixtures may not be mounted higher than 20 feet above average finished grade (§ 307-12.3).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An existing building with more than 20,000 square feet per floor is not treated as dimensionally nonconforming.
Community Commercial District - On a lot connected to a public sewer the minimum is 7,500 square feet of lot and 60 feet of width, with 5,000 square feet of land for each dwelling unit; the yards, the height and the coverage are the same either way.
- A building is capped at 12,000 square feet of floor area, or 75,000 square feet for a self-storage facility, and no single use other than a food store may occupy more than 4,000 square feet.
- At least 30 percent of the lot area must be landscaped, which is a minimum planting requirement and not a cap on paving.
- The height limit is stated as 2 1/2 stories or 35 feet, whichever is less.
- An active adult residential community needs a Planning Board special permit and at least eight acres, and is capped at 17 units per acre, 50 feet, three stories and 135,000 sq ft of floor area.
- A self-storage facility needs a Planning Board special permit, is limited to lots fronting Route 202 or Route 35, and takes the larger of the district figure or 40,000 sq ft of lot (§ 307-65.11).
- The Town Board may authorize a cluster subdivision in a CC district as well as in the residential districts (§ 307-19B(2)).
Designed Commercial District - A multifamily dwelling is allowed without a special permit only on a parcel that is also inside the Downtown Neighborhood Overlay, and there the overlay replaces the district's bulk standards for any building containing multifamily units (§ 307-96.4).
- Inside that overlay such a building needs 20,000 square feet of lot, 80 feet of width and 1,800 square feet of land per unit, and may reach 47 feet and four stories with 50 percent building coverage.
- The overlay also sets a maximum rather than a minimum front yard for such a building.
- At least 25 percent of the lot must be landscaped, a minimum planting requirement and not a cap on paving, and the landscaping along the street must be a continuous strip 25 feet wide (§ 307-21B(2)).
- The height limit is stated as 3 stories or 35 feet, whichever is less.
- A self-storage facility needs a Planning Board special permit, is limited to lots fronting Route 202 or Route 35, and takes the larger of the district figure or 40,000 sq ft of lot (§ 307-65.11).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
Conditional M-1 - The standards that govern COND M-1 parcels are not confirmed. Confirm them with the Town of Cortlandt Department of Technical Services before planning a building.
Highway Commercial District - A multifamily development needs a site of at least five acres and no more than 15 acres, and is allowed without a special permit only on a parcel that is also inside the Downtown Neighborhood Overlay (§ 307-65B(1)).
- It must be on municipal sewer or an approved disposal system and on a public or approved water supply.
- Inside that overlay such a building needs 20,000 square feet of lot, 80 feet of width and 1,800 square feet of land per unit, and may reach 47 feet and four stories with 50 percent building coverage.
- The overlay also sets a maximum rather than a minimum front yard for such a building.
- At least 30 percent of the lot must be landscaped, a minimum planting requirement and not a cap on paving, and the landscaping along the street must be a continuous strip 25 feet wide (§ 307-21B(2)).
- The height limit is stated as 2 1/2 stories or 35 feet, whichever is less.
- A self-storage facility needs a Planning Board special permit, is limited to lots fronting Route 202 or Route 35, and takes the larger of the district figure or 40,000 sq ft of lot (§ 307-65.11).
HC-9A District - The yards shown are for commercial use; a residential-only use owes 30 ft front, 10 ft side and 25 ft rear, and a mixed-use building owes 30 ft front, 25 ft side and 25 ft rear.
- A residential-only or mixed-use building needs 7,500 square feet of land for each dwelling unit and must keep 25 percent of the lot landscaped rather than 30 percent.
- That landscaping figure is a minimum planting requirement and not a cap on paving.
- Three and four-unit dwellings are limited to two bedrooms per unit.
- Single-family, two-family and three to four-family dwellings are permitted here, and a multifamily dwelling needs a special permit.
- The height limit is stated as 2 1/2 stories or 35 feet, whichever is less.
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
Light Industrial District - The landscaping separating buildings, parking and driveways from the street must be a continuous strip 25 feet wide (§ 307-21B(2)), and the height limit is given in feet alone, with no story limit.
- A contractor's yard or a specialty trade contractor is a special permit use whose own standards cap impervious coverage, including the buildings, at 55 percent of the site (§§ 307-65.5 and 307-65.6).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- An existing building with more than 20,000 square feet per floor is not treated as dimensionally nonconforming.
Camp Smith Reuse District B - The 5,000 square feet is land area for each dwelling unit rather than a minimum lot size, and the Town Board may reduce it by as much as 1,000 square feet on a lot where other land is preserved as open space by deed restriction (§ 307-95E(4)(a)).
- The code publishes no lot minimum, no lot width and no yard standards for the district.
- At least 25 percent of the lot must be kept as landscape coverage, which is a minimum planting requirement and not a cap on paving.
- Parks and recreation are the only uses of right; homes, retail, offices, lodging, institutional uses and manufacturing are all reachable only by Town Board special permit (§ 307-95B).
- The land uses must be mixed so that the residential area does not exceed the commercial and open space area.
- The maximum height may be modified by a local law providing for incentive zoning.
Conservation, Recreation and Open Space District - The district is not applied to an area of less than 25 acres unless the parcel is already encumbered by a conservation easement, a use restriction or a cluster subdivision set-aside (§ 307-12.2C).
- An accessory building may not stand in a front yard, is limited to 17 feet in height and needs 6 feet to the side and rear lines; one holding an accessory dwelling unit owes the main building's yards.
- All accessory structures together may not cover more than the main building's footprint, and no single one may exceed 70 percent of it.
- Each story may not exceed 12 feet.
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
- A building owned and occupied by a government agency or a public school may reach 75 feet if every yard is widened one foot for each extra foot of height (§ 307-18F).
Parks, Recreation and Open Space District - Chapter 307 publishes no dimensional figures for PROS.
- The general rules of § 307-18 still apply, including that on a corner lot every yard facing a street counts as a front yard for the main building.
Annsville Waterfront Enhancement District - Multifamily development is allowed outright only in the AWE-4 subarea and mixed-use only in the AWE-2, AWE-3 and AWE-4 subareas, at no more than five units per acre; the yards may be increased by the district's design guidelines.
- The bonuses are 70 feet of height in AWE-1, 15 units per acre with four stories or 50 feet in AWE-2, and 15 units per acre in AWE-3.
- In AWE-4 the bonus is 20 units per acre, or 40 units per acre with five stories or 55 feet where the project dedicates a publicly accessible waterfront walkway.
- A bonus is earned with an amenity package that must include infrastructure investment or a cash payment to the Town, and it needs municipal water and sewer on or reasonably adjacent to the site.
- Any multifamily unit is capped at 1,200 square feet, and a building with more than five units must set aside at least 10 percent of them as affordable under the Westchester County definition.
- An active adult residential community needs a Planning Board special permit and at least eight acres, and is capped at 17 units per acre, 50 feet, three stories and 135,000 sq ft of floor area.
- Multifamily in AWE-4 must include ground-floor commercial space at the Sprout Brook Road and Dogwood Road intersections on Albany Post Road.
M-1A District - Chapter 307 publishes no dimensional figures for M-1A.
- The district takes the same permitted uses as the Light Industrial district and adds the composting of organic waste (§ 307-96).
- Rock crushing is a special permit use that may be carried on only in this district (§ 307-65.9).
- Outdoor light fixtures may not be mounted higher than 20 feet above average finished grade (§ 307-12.3).
- On a corner lot every yard facing a street counts as a front yard for the main building (§ 307-18G).
ADUs vs. short-term rentals in Cortlandt
Short-term rentals allowed with local rules for Town of Cortlandt. Renting a home as transient lodging in the Town of Cortlandt requires a Town operating permit under Chapter 281, Transient and Nontransient Lodging, and the permit is a condition of continuing the use (§ 281-2). 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 minimum0.17–1.84 ac — an ADU still has to fit the district's lot and setback envelope.
- UtilityCon Edison territory.
- Zoning codeecode360.com/CO0244
- Building dept(914) 734-1010
ADU FAQ — Cortlandt, NY
Are ADUs allowed in Cortlandt, NY?
Town of Cortlandt has 21 districts. 12 districts allow ADUs with occupancy restrictions, 4 do not. 5 districts have incomplete data - verify with the building department at (914) 734-1010. Check your address with the free ADU checker.
Do I need a special permit for an ADU in Cortlandt?
No district in Town of Cortlandt requires a special-use permit for an ADU - 12 districts allow ADUs with occupancy restrictions, 4 do not. Site-plan review or a building permit may still apply.
Can I use an ADU as a short-term rental in Cortlandt?
Short-term rentals allowed with local rules for Town of Cortlandt. 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 Cortlandt
Permission is one question and budget is another. An 800 sq ft accessory unit here runs roughly $235k–310k 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 Cortlandt, priced by size.
How we know this
- Zoning code
- ecode360.com/CO0244
- Districts confirmed
- 16 of 21 — 5 not yet analyzed, so this page does not answer for them.
- 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 Cortlandt: Full zoning for new construction · ADU build cost · House build cost · ADU rules across Westchester County · All Westchester County towns
ADU information for Town of Cortlandt is compiled from the municipal code (last reviewed 2026-09-26) 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 (914) 734-1010 before relying on any answer. Source: the Offsite / Aldo zoning dataset.