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Tarrytown · ADU cost

What it costs to build an ADU in Tarrytown, NY

800 sq ft ≈ $235k–310k $296–388/sq ft 24 districts Con Edison

An 800 sq ft accessory dwelling unit in Tarrytown runs roughly $235k–310k, or about $296–388/sq ft, and that per-square-foot figure sits deliberately above the $242–318/sq ft a full house costs here. An ADU still needs one whole kitchen, one whole bath, its own service panel and its own heating plant no matter how small you draw it, and those costs do not shrink with the floor plan, so they land on half the square footage and push the rate up. Whether the village will let you build one is a separate question from what it costs, and it gets answered parcel by parcel rather than townwide, since the Village of Tarrytown maps 24 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.

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ADU cost by size in Tarrytown

Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Westchester County pricing, before the service and septic work a second dwelling can trigger.

SizeType$ / sq ftEstimated total
400 sq ft Studio $392–$514 $155k–205k
600 sq ft One bedroom $328–$430 $195k–260k
800 sq ft One bedroom, larger $296–$388 $235k–310k
1,000 sq ft Two bedroom $277–$362 $275k–360k

400 sq ft — One room plus a bath. Garage conversions and small backyard cottages land here.

600 sq ft — The most common detached build - a real bedroom, full kitchen, one bath.

800 sq ft — Room for a proper living area. Still a single bath and one kitchen.

1,000 sq ft — About as large as most codes allow an accessory unit to go.

Why the rate is higher than a house

The systems below are priced for an 800 sq ft unit. The middle column is what each system would cost if it simply shrank with the floor plan; the left column is what it actually costs once you account for the equipment a dwelling needs one of regardless of size. The gap between the two columns is the whole reason small builds price the way they do.

System$ / sq ft in an ADUIf it scaled with floor areaFixed per unit
Site work $9–$13 $9 —
Foundation $19–$27 $19 —
Framing $30–$38 $30 —
Envelope - roof, siding, windows $38–$49 $38 —
Plumbing $33–$40 $19 55%
Electrical $22–$28 $15 35%
HVAC $27–$34 $17 45%
Insulation $9–$11 $9 —
Interior finishes $38–$51 $32 15%
Millwork & cabinetry $22–$33 $13 55%

The fixed-per-unit share is a modeling assumption, not a figure from the code: it is our estimate of how much of each system's budget buys equipment a dwelling needs exactly one of - a kitchen rough-in, a bath group, a service panel, a heating plant - and therefore does not shrink when the unit does. Site work, foundation, framing, envelope and insulation are treated as scaling straight with floor area, which understates the premium slightly, because a small building carries more envelope per square foot of floor than a large one.

What the Tarrytown code says about accessory units

Whether you can build one, and how large, is decided by the district your parcel sits in rather than by the town as a whole. The table shows how each mapped district treats ADUs alongside the lot and setback standards a second unit still has to fit inside. District boundaries and conditions vary, so treat it as a starting point and confirm the district that applies to your parcel.

District Min lot Setbacks F / S / R Max height ADU
One-Family Residence 1.38 ac 40 / 25 / 45 ft 30 ft Occupancy restricted
One-Family Residence 1.84 ac 40 / 30 / 50 ft 30 ft Occupancy restricted
Historic Commons 5 ac 60 / 60 / 60 ft 35 ft No
One-Family Residence 0.69 ac 35 / 18 / 34 ft 30 ft Occupancy restricted
One-Family Residence 0.92 ac 40 / 20 / 36 ft 30 ft Occupancy restricted
One-Family Residence 0.23 ac 25 / 12 / 28 ft 30 ft Occupancy restricted
One-Family Residence 0.34 ac 27 / 14 / 30 ft 30 ft Occupancy restricted
One-Family Residence 0.46 ac 30 / 16 / 32 ft 30 ft Occupancy restricted
One-Family Residence 0.11 ac 20 / 8 / 26 ft 30 ft Occupancy restricted
One-Family Residence 0.17 ac 20 / 10 / 26 ft 30 ft Occupancy restricted
Multifamily Residence 0.34 ac 60 / 60 / 60 ft 35 ft No
Multifamily Residence 0.46 ac 70 / 70 / 70 ft 35 ft No
Multifamily Residence 0.11 ac 25 / 20 / 45 ft — No
Multifamily Residence 0.17 ac 25 / 20 / 45 ft — No
Multifamily Residence 0.23 ac 30 / 25 / 50 ft 35 ft No
Office Building 10 ac 100 / 50 / 50 ft 35 ft No
General Business 0.11 ac 10 / 0 / 10 ft 35 ft No
Limited Business 0.46 ac 30 / 16 / 32 ft 25 ft No
Neighborhood Shopping 0.11 ac 30 / 30 / 50 ft 35 ft No
Restricted Retail 0.11 ac 15 / 8 / 26 ft 25 ft No
Industrial — 10 / 10 / 40 ft 40 ft No
Waterfront General Business District 0.35 ac 30 / 30 / 30 ft 42 ft No
Mixed Use — 75 / 75 / 75 ft — No
Waterfront 0.35 ac 30 / 30 / 30 ft 42 ft No

One-Family Residence - A house may hold at most 8,700 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 10% and accessory buildings 2%.

  • On a lot of less than 60,000 sq ft the principal building may cover 12% and all buildings 14%.
  • Livable floor area may not exceed 1.5 times the principal building coverage.
  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 150 ft of street frontage is required as well.
  • A detached accessory building must sit at least 25 ft from the principal building and at least 25 ft from the side and rear lot lines.
  • The Planning Board may reduce the lot size, frontage and yards in R-60 and R-80 without adding lots, but never below the R-30 standards.

One-Family Residence - A house may hold at most 11,600 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 8% and accessory buildings 2%.

  • On a lot of more than 60,000 but less than 80,000 sq ft the principal building may cover 10% and all buildings 12%.
  • Livable floor area may not exceed 1.5 times the principal building coverage.
  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 150 ft of street frontage is required as well.
  • A detached accessory building must sit at least 30 ft from the principal building and at least 30 ft from the side and rear lot lines.
  • The Planning Board may reduce the lot size, frontage and yards in R-60 and R-80 without adding lots, but never below the R-30 standards.

Historic Commons - Residential density is at most one unit per five acres. A single-family residence or a park is allowed by right; multifamily housing, senior housing, an inn, a restaurant and cultural and religious institutions need a compatible use permit.

  • Of the coverage shown, principal buildings may cover 4% and accessory buildings 2%, with a further 4% for accessory areas that carry no building.
  • A multifamily building may hold at most 10 dwelling units.
  • Every use needs site development plan approval and a certificate of appropriateness from the Architectural Review Board.
  • New development must pass the viewshed assessment of § 305-38H.
  • An accessory building must sit at least 20 ft from the principal building and at least 50 ft from the side and rear lot lines.

One-Family Residence - A house may hold at most 6,000 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 16% and accessory buildings 4%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 135 ft of street frontage is required as well.
  • A detached accessory building must sit at least 18 ft from the principal building and at least 18 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A house may hold at most 6,500 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 14% and accessory buildings 3.5%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 150 ft of street frontage is required as well.
  • A detached accessory building must sit at least 20 ft from the principal building and at least 20 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A house may hold at most 3,500 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 22% and accessory buildings 5.5%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 100 ft of street frontage is required as well.
  • A detached accessory building must sit at least 12 ft from the principal building and at least 12 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A house may hold at most 4,350 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 20% and accessory buildings 5%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 115 ft of street frontage is required as well.
  • A detached accessory building must sit at least 14 ft from the principal building and at least 14 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A house may hold at most 5,200 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 18% and accessory buildings 4.5%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 120 ft of street frontage is required as well.
  • A detached accessory building must sit at least 16 ft from the principal building and at least 16 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A two-family dwelling is permitted here, with at least 2,000 sq ft of lot area per unit in a new building. A house may hold at most 2,150 sq ft of gross floor area, and one above that needs an area variance.

  • Each unit of a two-family dwelling needs at least 750 sq ft of livable floor area.
  • Building coverage is 30% for the principal building and none for accessory buildings.
  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 50 ft of street frontage is required as well.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

One-Family Residence - A house may hold at most 2,925 sq ft of gross floor area, and one above that needs an area variance. Within the building coverage shown, the principal building may cover 24% and accessory buildings 6%.

  • On a lot smaller than the district minimum a house takes a floor area ratio instead of that cap (§ 305-25B).
  • Lot width is measured at the front of the building, and at least 75 ft of street frontage is required as well.
  • A detached accessory building must sit at least 10 ft from the principal building and at least 10 ft from the side and rear lot lines.
  • Building walls may not cross a light exposure plane rising at 45 degrees from the neighboring setback lines.
  • A church needs a site of at least 2 acres and a community or recreation center at least 1 1/2 acres.

Multifamily Residence - A multifamily lot needs at least 15,000 sq ft for the first dwelling unit and at least 3,000 sq ft for each additional unit, and no building may hold more than four dwelling units.

  • A one-family dwelling instead needs yards of at least 27 ft in front, 14 ft on each side (30 ft combined) and 30 ft at the rear, and stands at most 2 1/2 stories and 25 ft.
  • A two-family dwelling instead needs yards of at least 40 ft in front, 40 ft on each side (80 ft combined) and 40 ft at the rear, and stands at most 2 stories and 25 ft.
  • A three-family dwelling needs a lot of at least 21,000 sq ft and yards of at least 45 ft in front, 45 ft on each side (90 ft combined) and 45 ft at the rear.
  • Multifamily buildings must stand apart by at least the height of the taller one, and never less than 25 ft.
  • Multifamily dwellings need site development plan approval from the Planning Board.
  • A nursing home needs a compatible use permit, a lot of at least 120,000 sq ft and at least 750 sq ft of lot area per bed.

Multifamily Residence - A multifamily lot needs at least 20,000 sq ft for the first dwelling unit and at least 4,000 sq ft for each additional unit, and no building may hold more than four dwelling units.

  • A one-family dwelling instead needs yards of at least 30 ft in front, 16 ft on each side (34 ft combined) and 32 ft at the rear, and stands at most 2 1/2 stories and 25 ft.
  • A two-family dwelling instead needs yards of at least 45 ft in front, 45 ft on each side (90 ft combined) and 45 ft at the rear, and stands at most 2 stories and 25 ft.
  • A three-family dwelling needs a lot of at least 28,000 sq ft and yards of at least 50 ft in front, 50 ft on each side (100 ft combined) and 50 ft at the rear.
  • Multifamily buildings must stand apart by at least the height of the taller one, and never less than 25 ft.
  • Multifamily dwellings need site development plan approval from the Planning Board.
  • A nursing home needs a compatible use permit, a lot of at least 120,000 sq ft and at least 750 sq ft of lot area per bed.

Multifamily Residence - A multifamily lot needs at least 5,000 sq ft for the first dwelling unit and at least 1,000 sq ft for each additional unit, and no building may hold more than four dwelling units.

  • A one-family dwelling instead needs yards of at least 20 ft in front, 8 ft on each side (18 ft combined) and 26 ft at the rear, and stands at most 2 1/2 stories and 30 ft.
  • A two-family dwelling instead needs yards of at least 15 ft in front and 10 ft on each side (20 ft combined), and all buildings may cover 55%.
  • A three-family dwelling needs a lot of at least 7,000 sq ft and yards of at least 20 ft in front, 15 ft on each side (30 ft combined) and 45 ft at the rear.
  • A side yard of at least 8 ft is required along a side lot line that adjoins another residence district.
  • Multifamily buildings must stand apart by at least the height of the taller one, and never less than 25 ft.
  • Multifamily dwellings need site development plan approval from the Planning Board.

Multifamily Residence - A multifamily lot needs at least 7,500 sq ft for the first dwelling unit and at least 1,500 sq ft for each additional unit, and no building may hold more than four dwelling units.

  • A one-family dwelling needs at least 75 ft of lot width and yards of at least 20 ft in front, 10 ft on each side (22 ft combined) and 26 ft at the rear, and stands at most 2 1/2 stories and 25 ft.
  • A two-family dwelling instead needs yards of at least 20 ft in front, 8 ft on each side (16 ft combined) and 26 ft at the rear, and stands at most 2 1/2 stories and 25 ft.
  • A three-family dwelling needs a lot of at least 11,500 sq ft and yards of at least 20 ft in front, 15 ft on each side (30 ft combined) and 45 ft at the rear.
  • A nursing home needs a compatible use permit, a lot of at least 120,000 sq ft and at least 120 ft of width, and at least 750 sq ft of lot area per bed.
  • Multifamily buildings must stand apart by at least the height of the taller one, and never less than 25 ft.
  • Multifamily dwellings need site development plan approval from the Planning Board.

Multifamily Residence - A multifamily lot needs at least 10,000 sq ft for the first dwelling unit and at least 2,500 sq ft for each additional unit, and no building may hold more than four dwelling units.

  • A one-family dwelling needs at least 100 ft of lot width and yards of at least 25 ft in front, 12 ft on each side (26 ft combined) and 28 ft at the rear, and stands at most 2 1/2 stories and 25 ft.
  • A two-family dwelling instead needs yards of at least 20 ft in front, 8 ft on each side (18 ft combined) and 26 ft at the rear, with at least 750 sq ft of livable floor area per unit.
  • A three-family dwelling needs a lot of at least 15,000 sq ft and yards of at least 25 ft in front, 20 ft on each side (40 ft combined) and 45 ft at the rear.
  • Multifamily buildings must stand apart by at least the height of the taller one, and never less than 25 ft.
  • Multifamily dwellings need site development plan approval from the Planning Board.
  • A nursing home needs a compatible use permit, a lot of at least 120,000 sq ft and at least 750 sq ft of lot area per bed.

Office Building - All buildings, structures and paved areas must be set back at least 100 ft from the right-of-way of any public street and from any residential zoning district, and at least 50 ft from any nonresidential district or other property boundary.

  • Coverage is measured against the buildable site area, the lot area less half the area of wetlands and slopes of 25% or more.
  • Building coverage may rise by 1% for each additional 5% of parking enclosed in garages above the 20% minimum, up to 17%, and the floor area ratio rises with it to 0.51.
  • Lot width is measured at the front of the building, where at least 400 ft is required.
  • Buildings and structures must sit at least 50 ft, and paved areas at least 25 ft, from the right-of-way of the New York State Thruway or its Administrative Headquarters.
  • No wall may be taller than 40% of its distance to the nearest street or property line.
  • An accessory use must sit at least 150 ft from any street or property line.

General Business - The figures shown are for a business structure. Where any part of the building is used for residences the rear yard must be at least 15 ft deep, and a residential structure instead needs a lot of at least 20,000 sq ft.

  • A residential structure needs at least 120 ft of lot width, yards of at least 30 ft in front, 16 ft on each side (34 ft combined) and 32 ft at the rear, and may cover 22.5% with all buildings.
  • A side yard of at least 8 ft is required along a side lot line that adjoins a residence district.
  • A parking buffer at least 15 ft wide is required along any side or rear boundary that adjoins a residence district.
  • Two-family dwellings and dwelling space above a permitted use are also permitted.

Limited Business - The figures shown are for a one-family residence. One- and two-family dwellings are the district's by-right uses, and a business use needs a compatible use permit.

  • A business structure east of Route 9 needs at least 1 acre, 150 ft of width and yards of at least 60 ft in front, 35 ft on each side (70 ft combined) and 60 ft at the rear.
  • West of Route 9 a business structure needs at least 217,800 sq ft, 400 ft of width and yards of at least 60 ft in front, 60 ft on each side (120 ft combined) and 60 ft at the rear.
  • A restaurant or a technical training center needs a lot of at least 217,800 sq ft, at least 400 ft of width and yards of at least 60 ft in front, on each side and at the rear.
  • A hotel needs a lot of at least 435,600 sq ft, at least 450 ft of width and yards of at least 70 ft in front, 50 ft on each side (100 ft combined) and 50 ft at the rear.
  • A hotel needs at least 3,000 sq ft of lot area per unit in a one-story building, or at least 1,500 sq ft per unit in a building of two or more stories.
  • No wall of a business structure east of Route 9 may be taller than 40% of its distance to any street or property line.

Neighborhood Shopping - The figures shown are for commercial and other permitted uses. A one-family dwelling instead needs a lot of at least 20,000 sq ft, at least 120 ft of width and yards of at least 30 ft in front, 16 ft on each side (34 ft combined) and 32 ft at the rear.

  • A one-family dwelling needs site plan approval from the Planning Board and the concurrence of the Board of Trustees.
  • No accessory buildings are permitted in NS.
  • A two-family dwelling needs at least 2,000 sq ft of lot area per unit in a new building, and at least 750 sq ft of livable floor area for each unit.
  • A church needs a site of at least 2 acres and a community center at least 1 1/2 acres.

Restricted Retail - The figures shown are for a business structure. A one-family dwelling instead needs a lot of at least 20,000 sq ft, at least 120 ft of width and yards of at least 30 ft in front, 16 ft on each side (34 ft combined) and 32 ft at the rear.

  • A business structure on Broadway needs a front yard of at least 20 ft.
  • Dwelling space above a business use needs at least 1,000 sq ft of lot area and at least 600 sq ft of floor area per unit, and may reach 3 stories and 35 ft.
  • A side yard of at least 8 ft is required along a side lot line that adjoins a residence district.
  • A parking buffer at least 15 ft wide is required along any side or rear boundary that adjoins a residence district.
  • Two-family dwellings are also permitted.

Industrial - Multifamily housing above first-floor nonresidential uses is permitted as transit-oriented development on a parcel of at least one acre within 100 ft of access to the Metro-North platform, at up to 75 units per acre, 4 stories and 48 ft.

  • At least half of the first floor of such a building must be nonresidential.
  • That floor area ratio of 1.75 counts residential floor area only, without the entry lobby and amenity space.
  • On a lot that abuts the railroad tracks the rear yard may be reduced to zero.
  • Along any municipal boundary a landscaped strip at least 5 ft wide, with 6 ft planting and decorative fencing, is required in addition to the side and rear yards.
  • Lumber and similar combustible material may not be stored within 15 ft of a side or rear lot line bordering a residential district.

Waterfront General Business District - Building coverage of 35% is measured against the dry land area of the lot, and no structure that is not water dependent may sit within 50 ft of the mean high-water mark of the Hudson River.

  • A use that needs a compatible use permit requires at least 200 ft of both width and depth.
  • At least 125 ft of public street frontage is required, and lot depth is measured from the shoreline to the railroad tracks.
  • A pitched roof may reach 45 ft, and a townhouse 35 ft with a flat roof or 45 ft with a pitched roof that does not start above 32 ft.
  • Buildings, structures, fences and walls over 30 inches may together occupy at most 40% of the parcel width.
  • For public benefit features the Board of Trustees may grant incentives: 55% building coverage, 65% building width, 0 ft front and side yards, a 10 ft rear yard and 75 ft of street frontage.
  • A flat-roofed building may reach 5 stories and 52 ft by special permit of the Board of Trustees.

Mixed Use - Every use here needs a compatible use permit. At least 40% of the gross floor area must be office use, and between 40% and 55% residential.

  • Only parcels the Board of Trustees designates, zoned OB on June 1, 1979, of at least 50 contiguous acres and fronting a state highway and the Thruway for at least 20% of the perimeter each.
  • Buildings must sit at least 50 ft from the New York State Thruway right-of-way, at least 100 ft from Route 119 and at least 75 ft from all other property lines.
  • Buildings on the same lot must stand at least 50 ft apart.
  • Paved areas must sit at least 25 ft from the Thruway right-of-way, at least 50 ft from Route 119, at least 75 ft from any residential district and at least 50 ft from other property lines.
  • Nothing built or impervious may lie within 75 ft of a wetland.
  • Building coverage may rise by 1% for each additional 5% of parking enclosed in garages above the 20% minimum, up to 17%, and impervious surfaces other than buildings may cover 33%.

Waterfront - Building coverage of 35% is measured against the dry land area of the lot, and no structure that is not water dependent may sit within 50 ft of the mean high-water mark of the Hudson River.

  • A use that needs a compatible use permit requires at least 200 ft of both width and depth.
  • At least 125 ft of public street frontage is required, and lot depth is measured from the shoreline to the railroad tracks.
  • A pitched roof may reach 45 ft, and a townhouse 35 ft with a flat roof or 45 ft with a pitched roof that does not start above 32 ft.
  • Buildings, structures, fences and walls over 30 inches may together occupy at most 40% of the parcel width.
  • For public benefit features the Board of Trustees may grant incentives: 55% building coverage, 65% building width, 0 ft front and side yards, a 10 ft rear yard and 75 ft of street frontage.
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Size limits on record in Tarrytown

Where the code states a size cap, it decides which row of the cost table above actually applies to you. These are the caps recorded for Tarrytown:

Costs an ADU adds that a house does not

Sizing up a specific parcel in Tarrytown?

Aldo pulls the exact zoning district, setbacks, and build feasibility for any parcel — before you buy. Enter your email to open Aldo and run your free report.

Building a full house instead?

A standard-finish house in Tarrytown runs $242–318/sq ft, about $435k–570k at 1,800 sq ft . See what it costs to build a house in Tarrytown.

ADU cost in nearby towns

Mount Vernon (City)
800 sq ft ≈ $235k–310k
New Rochelle (City)
800 sq ft ≈ $235k–310k
Peekskill (City)
800 sq ft ≈ $235k–310k
Rye (City)
800 sq ft ≈ $235k–310k
White Plains (City)
800 sq ft ≈ $235k–310k
Yonkers (City)
800 sq ft ≈ $235k–310k

All Westchester County towns: Mount Vernon (City) · New Rochelle (City) · Peekskill (City) · Rye (City) · White Plains (City) · Yonkers (City) · Bedford · Cortlandt · Eastchester · Greenburgh · Lewisboro · Mamaroneck · Mount Pleasant · New Castle · North Castle · North Salem · Ossining · Pound Ridge · Somers · Yorktown · Harrison (Village) · Ardsley (Village) · Briarcliff Manor (Village) · Bronxville (Village) · Buchanan (Village) · Croton-on-Hudson (Village) · Dobbs Ferry (Village) · Elmsford (Village) · Hastings-on-Hudson (Village) · Irvington (Village) · Larchmont (Village) · Mamaroneck (Village) · Mount Kisco (Village) · Ossining (Village) · Pelham (Village) · Pelham Manor (Village) · Pleasantville (Village) · Port Chester (Village) · Rye Brook (Village) · Scarsdale (Village) · Sleepy Hollow (Village) · Tuckahoe (Village)

More on Tarrytown: Can you build an ADU here? · Zoning for new construction · Westchester County build cost

ADU cost in Tarrytown: common questions

How much does it cost to build an ADU in Tarrytown, NY?

An 800 sq ft accessory dwelling unit in Village of Tarrytown runs roughly $235k–310k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $155k–205k. Those are structure costs on an easy site and do not include the septic, water or electrical service work a second unit often triggers.

Why does an ADU cost more per square foot than a house in Tarrytown?

Because a lot of a dwelling's cost is per dwelling, not per square foot. One kitchen, one bath group, one service panel and one heating plant cost about the same in an 800 sq ft cottage as in a 1,800 sq ft house, so on the smaller unit they get spread over less than half the floor area. That is why an ADU here prices at $296–388/sq ft against $242–318/sq ft for a full house, even though it is the same trades doing the same work.

Are ADUs allowed in Tarrytown?

Village of Tarrytown has 24 districts. 15 districts prohibit ADUs, 9 allow them with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (914) 631-3668 before you spend money on design.

Can I rent an ADU in Tarrytown short term?

No local short-term-rental law on record - which is not the same as permission for Village of Tarrytown. ADU rules and short-term-rental rules are set separately, so a unit you are allowed to build is not automatically one you are allowed to rent nightly. Confirm both before you underwrite the build on short-term-rental income.

ADU costs are modeled estimates in current 2026 dollars at the Westchester County regional index, general-contractor margin included, derived from Offsite's cost engine with a stated adjustment for the equipment a dwelling needs one of regardless of size. They are planning numbers for decision-support only - not a bid, quote, or guarantee, and not legal, architectural or engineering advice. They cover the structure and exclude septic expansion, utility service runs, site work beyond a flat and clear pad, and permit fees. ADU eligibility, size, owner-occupancy and permit conditions in the Village of Tarrytown vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-09-21; verify with the building department at (914) 631-3668 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.

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