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Greenburgh · ADU cost

What it costs to build an ADU in Greenburgh, NY

800 sq ft ≈ $235k–310k $296–388/sq ft 27 districts Con Edison

An 800 sq ft accessory dwelling unit in Greenburgh 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 town 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 Town of Greenburgh maps 27 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 Greenburgh

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 Greenburgh 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 District 0.69 ac 35 / 20 / 34 ft 30 ft Occupancy restricted
One-Family Residence District 0.92 ac 40 / 25 / 36 ft 30 ft Occupancy restricted
Multifamily District — 60 / 60 / 60 ft 25 ft No
Planned Unit Development District 15 ac — 25 ft Occupancy restricted
One-Family Residence District 0.23 ac 25 / 12 / 28 ft 30 ft Occupancy restricted
One-Family Residence District 0.34 ac 27 / 14 / 30 ft 30 ft Occupancy restricted
One-Family Residence District 0.46 ac 30 / 18 / 32 ft 30 ft Occupancy restricted
One-Family Residence District 0.11 ac 20 / 8 / 26 ft 30 ft Occupancy restricted
One-Family Residence District 0.17 ac 20 / 10 / 26 ft 30 ft Occupancy restricted
Multifamily Residence District — 50 / 50 / 55 ft 38 ft No
Multifamily Residence District — 40 / 40 / 40 ft 38 ft No
Scatter-Site Public Housing District — 40 / 40 / 40 ft 25 ft No
Multifamily Residence District — 40 / 40 / 40 ft 38 ft No
High-Rise Multifamily Residence District — 50 / 50 / 60 ft 68 ft No
High-Rise Multifamily Residence District — 10 / 10 / 30 ft 68 ft No
Central Avenue Mixed-Use Impact District — 40 / 20 / 25 ft 48 ft No
Close Business District — 20 / 10 / 50 ft 25 ft No
Designed Shopping District 0.23 ac 20 / 15 / 50 ft 40 ft No
Hartsdale Center District — — 30 ft No
Intermediate Business — 20 / 20 / 50 ft 25 ft No
Limited Office Building District 0.46 ac 25 / 20 / 50 ft 55 ft No
Office Building District 1.84 ac 150 / 150 / 150 ft 75 ft No
Office Building District 0.92 ac 40 / 20 / 50 ft 40 ft No
General Industrial District 1.84 ac 50 / 100 / 65 ft 45 ft No
Light Industrial District 0.92 ac 40 / 50 / 50 ft 45 ft No
Nonresidential Planned Development District 35 ac — 40 ft No
Urban Renewal District 0.11 ac 20 / 10 / 25 ft 25 ft No

One-Family Residence District - A one-family dwelling may reach 35 ft, still 2 1/2 stories, on a lot of 80,000 sq ft or more, but only with yards of at least 60 ft front, 36 ft on one side, 80 ft for both sides and 64 ft rear.

  • Floor area for a one-family dwelling runs on a lot-size ladder, 0.20 on a 30,000 sq ft lot down to 0.115 at 100,000 sq ft.
  • Above 100,000 sq ft, a one-family dwelling of more than 11,500 sq ft needs a Planning Board special permit.
  • Of the 20% building coverage, the principal building may take 16% and accessory buildings 4%.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 18 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

One-Family Residence District - A one-family dwelling may reach 35 ft, still 2 1/2 stories, on a lot of 80,000 sq ft or more, but only with yards of at least 60 ft front, 36 ft on one side, 80 ft for both sides and 64 ft rear.

  • Floor area for a one-family dwelling runs on a lot-size ladder, 0.175 on a 40,000 sq ft lot down to 0.115 at 100,000 sq ft.
  • Above 100,000 sq ft, a one-family dwelling of more than 11,500 sq ft needs a Planning Board special permit.
  • Of the 17.5% building coverage, the principal building may take 14% and accessory buildings 3.5%.
  • Several uses allowed by special permit carry their own larger lot minimums, at least two acres.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 20 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

Multifamily District - Unit count comes from the buildable area rather than the whole lot: it deducts 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses, then divides by the land needed per unit.

  • No minimum lot size or width is set for the district.
  • A multifamily building may be no more than 140 ft long.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • Of the 15% building coverage, the principal building may take 12% and accessory buildings 3%.
  • Detached accessory buildings and parking must sit at least 20 ft from the side and rear lot lines and at least 10 ft from the principal building.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

Planned Unit Development District - The site must be at least 15 acres and large enough for 50 dwelling units, and the unit count is the total land area divided by the minimum lot size of the district the site lies in, less 25%. An approved plan replaces the district dimensions.

  • A buffer at least 75 ft deep runs along the property line and street lines, 25 ft where the development is single-family detached homes, and no building or parking may sit in it.
  • No building may be within 50 ft of the property line.
  • Lots inside the development have no minimum size, frontage or coverage, and the Planning Board is guided by the standards for comparable uses.
  • Principal buildings must stand at least as far apart as their average height, 15 ft for single-family detached homes.
  • Any building must be set back at least 25 ft from an interior street that carries through traffic.
  • No more than six dwelling units may be grouped in one attached building, and open space of at least 500 sq ft per bedroom is required.

One-Family Residence District - Floor area for a one-family dwelling runs on a lot-size ladder, 0.325 on a 10,000 sq ft lot down to 0.115 at 100,000 sq ft; above 100,000 sq ft, a dwelling of more than 11,500 sq ft needs a Planning Board special permit.

  • Of the 27.5% building coverage, the principal building may take 22% and accessory buildings 5.5%.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 12 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

One-Family Residence District - Floor area for a one-family dwelling runs on a lot-size ladder, 0.275 on a 15,000 sq ft lot down to 0.115 at 100,000 sq ft; above 100,000 sq ft, a dwelling of more than 11,500 sq ft needs a Planning Board special permit.

  • Of the 25% building coverage, the principal building may take 20% and accessory buildings 5%.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 14 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

One-Family Residence District - A one-family dwelling may reach 35 ft, still 2 1/2 stories, on a lot of 80,000 sq ft or more, but only with yards of at least 60 ft front, 36 ft on one side, 80 ft for both sides and 64 ft rear.

  • Floor area for a one-family dwelling runs on a lot-size ladder, 0.25 on a 20,000 sq ft lot down to 0.115 at 100,000 sq ft.
  • Above 100,000 sq ft, a one-family dwelling of more than 11,500 sq ft needs a Planning Board special permit.
  • Of the 22.5% building coverage, the principal building may take 18% and accessory buildings 4.5%.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 16 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

One-Family Residence District - Floor area for a one-family dwelling runs on a lot-size ladder, 0.45 on a 5,000 sq ft lot down to 0.115 at 100,000 sq ft; above 100,000 sq ft, a dwelling of more than 11,500 sq ft needs a Planning Board special permit.

  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building must sit at least 8 ft from the principal building and at least 8 ft from the side and rear lot lines.

One-Family Residence District - Floor area for a one-family dwelling runs on a lot-size ladder, 0.35 on a 7,500 sq ft lot down to 0.115 at 100,000 sq ft; above 100,000 sq ft, a dwelling of more than 11,500 sq ft needs a Planning Board special permit.

  • Of the 30% building coverage, the principal building may take 24% and accessory buildings 6%.
  • A flag lot needs twice the minimum lot area, not counting its access strip, and every lot needs at least 25 ft of frontage on a public street.
  • A detached accessory building or off-street parking area must sit at least 10 ft from the side and rear lot lines, and a detached accessory building at least 10 ft from the house.

Multifamily Residence District - The yards shown are for a two-story building; a three-story building needs at least 60 ft front, 60 ft on one side and 120 ft for both, and 60 ft rear.

  • A three-story building may cover 15% with all buildings and 34% with impervious surfaces, against 20% and 39% for a two-story building.
  • No minimum lot size or width is set for the district.
  • Unit count is the buildable area divided by the land needed per unit, deducting 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses.
  • A multifamily building may be no more than 180 ft long.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

Multifamily Residence District - The yards shown are for a two-story building; a three-story building needs at least 45 ft on every yard, and 90 ft for both sides combined.

  • A three-story building may cover 19% with all buildings and 43% with impervious surfaces, against 25% and 49% for a two-story building.
  • No minimum lot size or width is set for the district.
  • Unit count is the buildable area divided by the land needed per unit, deducting 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • Detached accessory buildings and parking must sit at least 10 ft from the side and rear lot lines and at least 10 ft from the principal building.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

Scatter-Site Public Housing District - The figures shown are for a public housing project of 15 units or fewer. A project of 16 to 25 units needs 6,500 sq ft of lot area per dwelling unit, with all buildings covering 12% and impervious surfaces 25%; the yards and the height are the same.

  • For a project of 15 units or fewer, the principal building may cover 11.5% and accessory buildings 4.5%.
  • For a project of 16 to 25 units, the principal building may cover 8.5% and accessory buildings 3.5%.
  • No minimum lot size or width is set for the district.
  • Multifamily dwellings here must be financed as public housing.
  • Any principal use of the R-10 District is also allowed.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.

Multifamily Residence District - The yards shown are for a two-story building; a three-story building needs at least 45 ft on every yard, and 90 ft for both sides combined.

  • A three-story building may cover 27% with all buildings and 58.5% with impervious surfaces, against 36% and 67.5% for a two-story building.
  • No minimum lot size or width is set for the district.
  • Unit count is the buildable area divided by the land needed per unit, deducting 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • Detached accessory buildings and parking must sit at least 10 ft from the side and rear lot lines and at least 10 ft from the principal building.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

High-Rise Multifamily Residence District - Unit count comes from the buildable area rather than the whole lot: it deducts 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses, then divides by the land needed per unit.

  • No minimum lot size or width is set for the district.
  • Of the 15% building coverage, the principal building may take 10% and accessory buildings 5%.
  • Accessory buildings are limited to one story and 12 ft.
  • Detached accessory buildings and parking must sit at least 10 ft from the principal building and from the side and rear lot lines.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

High-Rise Multifamily Residence District - Each dwelling unit needs at least 250 sq ft of lot area, which makes M-174 the densest multifamily district in the Town.

  • No minimum lot size or width is set for the district.
  • Accessory buildings are limited to one story and 12 ft.
  • On a lot on a street at least 100 ft wide, offices and restaurants are allowed as accessory uses by special permit, with a 15 ft landscaped strip between the street line and any pavement or parking.
  • Unit count is the buildable area divided by the land needed per unit, deducting 20% of steep slopes, 50% of very steep slopes and 75% of excessively steep slopes, wetlands and watercourses.
  • Each dwelling unit needs at least 600 sq ft of livable floor area, and at least 450 sq ft for a studio.
  • One-family detached dwellings are also a principal use, in accordance with the R-10 District.

Central Avenue Mixed-Use Impact District - The yards shown are for a lot under 50,000 sq ft; a lot of 50,000 sq ft or more needs at least 80 ft front, 40 ft side and 50 ft rear.

  • Floor area ratio and height vary by use: office, conference center and clinic 0.30 at 4 stories and 48 ft, research 0.35, telephone exchange 0.45, and post office 0.15 at 2 stories and 24 ft.
  • Retail, personal service and other commercial uses take 0.10, or 0.135 on a site of two acres or less, at 2 stories and 24 ft.
  • In a multiple-use development the ratios rise, office to 0.35 and retail and personal service to 0.125.
  • Multifamily development needs at least two acres, with an average livable floor area of at least 750 sq ft per unit, and is limited to 35 bedrooms per acre (40 in a multiple-use development).
  • Motor vehicle sales by Planning Board special permit need 40,000 sq ft, with a 0.35 floor area ratio and 2 1/2 stories and 30 ft.
  • No minimum lot size or width and no building coverage cap are set.

Close Business District - In a mixed-use building, banking, retail and personal service uses are limited to the first floor and to 33% of the building floor area.

  • No minimum lot area or width is set for the district.
  • Parking must sit at least 10 ft from the side and rear lot lines and from the principal building.

Designed Shopping District - The yards shown are for a lot of 10,000 to 40,000 sq ft; larger lots need deeper yards.

  • A lot of 40,000 to 90,000 sq ft needs at least 30 ft front, 40 ft on one side and 80 ft for both, and 50 ft rear.
  • A lot of 90,000 sq ft or more needs at least 40 ft front, 45 ft on one side and 90 ft for both, and 60 ft rear.
  • All buildings may cover 25% of a lot of 40,000 to 90,000 sq ft, and 20% of a lot of 90,000 sq ft or more.
  • Impervious surfaces may cover 80% on any lot.
  • Parking must sit at least 20 ft from the front lot line and at least 10 ft from the side and rear lot lines and the principal building.

Hartsdale Center District - No specific minimum front, side or rear yard is set (§ 285-29.2C(1)(c)). The Planning Board sets yards case by case at site plan review, for design, circulation and buffering.

  • No minimum lot area and no coverage cap are set.

Intermediate Business - No minimum lot area or width and no floor area ratio are set for the district.

  • Existing detached dwellings follow the R-5 District lot and bulk rules.
  • Detached accessory buildings and parking must sit at least 10 ft from the side and rear lot lines and from the principal building.

Limited Office Building District - Retail and personal service use of the first floor of an office building may not exceed 25% of its floor area.

  • Detached dwellings are also allowed as regulated in the R-10 District.
  • Parking must sit at least 15 ft from the front lot line and at least 10 ft from the side and rear lot lines and the principal building.

Office Building District - The 150 ft front yard is waived for a building that bridges a public highway to connect two commonly owned parcels, subject to its own clearance and setback conditions.

  • Of the 22.5% building coverage, the principal building may take 18% and accessory buildings 4.5%.
  • Detached accessory buildings and parking must sit at least 50 ft from every lot line and at least 25 ft from the principal building.
  • A hotel by Town Board special permit, on 15 acres or more adjoining an interstate, may reach 10 stories and 110 ft, with 1,150 sq ft of lot area per rentable room.
  • Retail and restaurants by Town Board special permit need 15 acres, and a college needs 100 acres.
  • Precision parts assembly by special permit needs 200,000 sq ft, 500 ft of width, yards of 250 ft (500 ft for both sides), 25% building and 65% impervious coverage, and 72 ft height.

Office Building District - Of the 25% building coverage, the principal building may take 20% and accessory buildings 5%.

  • The principal uses are those of the OB District.
  • Detached accessory buildings and parking must sit at least 10 ft from every lot line and from the principal building; off-street parking and loading need at least 15 ft from any lot line or street.

General Industrial District - No floor area ratio is set for the district, and of the 20% building coverage the principal building may take 15% and accessory buildings 5%.

  • Detached accessory buildings and parking must sit at least 25 ft from the side and rear lot lines and the principal building.
  • An animal shelter by Town Board special permit needs 130,000 sq ft, keeps buildings 30 ft from street and lot lines and 200 ft from any dwelling, and is limited to a 0.35 floor area ratio.

Light Industrial District - No floor area ratio is set for the district, and of the 20% building coverage the principal building may take 15% and an accessory building 5%.

  • Outdoor storage must sit at least 25 ft from any lot line and stand no more than 6 ft high.
  • Detached accessory buildings and parking must sit at least 25 ft from the side and rear lot lines and the principal building.

Nonresidential Planned Development District - A planned development needs at least 35 contiguous acres, and the lots it is divided into need at least 80,000 sq ft each.

  • A 100 ft buffer surrounds the development.
  • No building may be within 200 ft of residential property or a residential district, 100 ft where that land is a utility right-of-way.
  • No building may be within 100 ft of a district boundary, external lot line or state or county road, or within 50 ft of an internal lot line or internal street.
  • The floor area ratio is 0.30 for all structures and 0.08 for commercial uses.
  • Open storage counts as building coverage against the 40% cap.
  • Lot sizes, frontage and coverage of individual lots are otherwise left to the approved comprehensive plan.

Urban Renewal District - The Urban Renewal Plan designates the land use of each parcel, and the Town Board must approve a comprehensive development plan before any site is developed. The figures shown are the Residential A single-family row.

  • A two-family dwelling needs a lot of at least 6,000 sq ft and 3,000 sq ft per unit, with the same coverage, height and yards.
  • Garden apartments and townhouses need at least 10,000 sq ft and 2,000 sq ft per unit, may cover 35%, and need 20 ft front, 25 ft rear and 10 ft on each side.
  • In Residential B, elevator apartments need 20,000 sq ft and 1,500 sq ft per unit, may cover 15%, may reach 7 stories and 85 ft, and need 50 ft front, 60 ft rear and 50 ft on each side.
  • In Residential C, garden apartments need 10,000 sq ft and 3,750 sq ft per unit, may cover 20%, are limited to 2 stories and 25 ft, and need 40 ft on every yard.
  • A one-family dwelling needs at least 1,050 sq ft of livable floor area, and a unit in any other dwelling 600 sq ft.
  • Neighborhood shopping and general commercial uses need 10,000 sq ft, may cover 30%, 2 stories and 25 ft, with 10 ft front and 25 ft rear, 50 ft next to a residential district.
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Size limits on record in Greenburgh

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 Greenburgh:

Costs an ADU adds that a house does not

Sizing up a specific parcel in Greenburgh?

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

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 · 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) · Tarrytown (Village) · Tuckahoe (Village)

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

ADU cost in Greenburgh: common questions

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

An 800 sq ft accessory dwelling unit in Town of Greenburgh 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 Greenburgh?

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 Greenburgh?

Town of Greenburgh has 27 districts. 19 districts prohibit ADUs, 8 allow them with occupancy restrictions. Check the specific address with the free ADU checker or confirm with the building department at (914) 989-1560 before you spend money on design.

Can I rent an ADU in Greenburgh short term?

No local short-term-rental law on record - which is not the same as permission for Town of Greenburgh. 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 Town of Greenburgh 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) 989-1560 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.

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