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Yonkers · ADU cost

What it costs to build an ADU in Yonkers, NY

800 sq ft ≈ $235k–310k $296–388/sq ft 34 districts Con Edison

An 800 sq ft accessory dwelling unit in Yonkers 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 city 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 City of Yonkers maps 34 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 Yonkers

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 Yonkers 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
Planned Urban Redevelopment 2 ac — — No
Detached Single-Family Dwellings 0.46 ac 25 / 20 / 25 ft 35 ft No
Detached Single-Family Dwellings 0.23 ac 25 / 15 / 25 ft 35 ft No
Detached Single-Family Dwellings 0.14 ac 20 / 8 / 25 ft 35 ft No
Detached Single-Family Dwellings 0.17 ac 25 / 11 / 25 ft 35 ft No
Detached Single-Family Dwellings 0.11 ac 20 / 6 / 25 ft 35 ft No
Apartment Houses, Low-Density 0.11 ac 20 / 6 / 25 ft 35 ft No
Two-Family Dwellings 0.11 ac 20 / 6 / 25 ft 35 ft No
Apartment Houses, High-Density 0.11 ac 20 / 6 / 25 ft 35 ft No
Apartment Houses, Medium-Density 0.11 ac 20 / 6 / 25 ft 35 ft No
Planned Industrial, Residences Excluded 4.02 ac 50 / 50 / 50 ft 35 ft No
Planned Executive Park 30 ac 50 / 50 / 50 ft 55 ft No
Neighborhood Business and Apartment Houses, Medium-Density 0.11 ac 20 / 6 / 25 ft 35 ft No
General Business and Apartment Houses, High-Density 0.11 ac 20 / 6 / 25 ft 35 ft No
Restricted Business, Residences Excluded 0.23 ac 25 / 25 / 25 ft 48 ft No
Central Business District — - / - / 10 ft 50 ft No
Downtown Waterfront District — - / - / 10 ft 66 ft No
Office Buildings and Research Laboratories, Residences Excluded 0.17 ac 25 / 10 / 25 ft 45 ft No
Wholesale Business and Storage — - / 5 / 20 ft — No
Commercial, Storage and Light Manufacturing, Residences Excluded 0.23 ac 20 / 16 / 20 ft 35 ft No
Industry, Residences Excluded — - / 0 / 20 ft — No
Colleges, Universities and Theological Seminaries 0.34 ac 25 / 15 / 25 ft 39 ft No
Government Center District — - / - / 10 ft 100 ft No
Planned Multi-Use Development 80 ac — 90 ft No
Culture and Arts 0.34 ac 25 / 15 / 25 ft 39 ft —
Ludlow Mixed-Use District — 0 / - / 10 ft 65 ft —
Artisans & Industry Special District — - / 0 / 20 ft — —
Austin Avenue Special Shopping District 0.46 ac 10 / - / - ft 65 ft —
South Broadway District — 0 / 0 / 10 ft — —
Mixed-Use District — 0 / 0 / 0 ft 66 ft —
Downtown Industrial Research and Technology District — 0 / 0 / 0 ft 66 ft —
Low Density Urban Residential District 0.057 ac 5 / - / 25 ft 35 ft —
Medium Density Urban Residential District 0.057 ac 5 / - / 25 ft 35 ft —
High Density Urban Residential District — 0 / 0 / 20 ft 66 ft —

Planned Urban Redevelopment - The code establishes no PDR district. A planned urban redevelopment is a special use permit available in designated urban renewal areas in any district on a tract of two or more acres (§ 43-72C).

  • Such a development need not meet its district's dimensional or use requirements; its dimensions are those of the comprehensive development plan approved by the Planning Board and the City Council.
  • What is built under the permit is deemed conforming.
  • To learn which district a PDR parcel carries, ask the City of Yonkers Department of Planning and Development.

Detached Single-Family Dwellings - The figures shown are for single- and two-family dwellings. The 0.56 floor area ratio applies only to the first 20,000 sq ft of lot; lot area beyond 20,000 sq ft counts at 0.38.

  • On a corner lot, the side front yard is at least 25 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 20,000 sq ft and at least 200 ft of width, with a 0.75 floor area ratio.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Detached Single-Family Dwellings - The figures shown are for single- and two-family dwellings. The 0.56 floor area ratio applies only to the first 10,000 sq ft of lot; lot area beyond 10,000 sq ft counts at 0.38.

  • On a corner lot, the side front yard is at least 25 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with a 0.75 floor area ratio.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Detached Single-Family Dwellings - The figures shown are for single- and two-family dwellings. The 0.68 floor area ratio applies only to the first 6,000 sq ft of lot; lot area beyond 6,000 sq ft counts at 0.46.

  • On a corner lot, the side front yard is at least 12 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with a 0.90 floor area ratio.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Detached Single-Family Dwellings - The figures shown are for single- and two-family dwellings. The 0.60 floor area ratio applies only to the first 7,500 sq ft of lot; lot area beyond 7,500 sq ft counts at 0.40.

  • On a corner lot, the side front yard is at least 20 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with a 0.80 floor area ratio.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Detached Single-Family Dwellings - The figures shown are for single- and two-family dwellings. The 0.75 floor area ratio applies only to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.50.

  • On a corner lot, the side front yard is at least 10 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with a 1.00 floor area ratio.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Apartment Houses, Low-Density - Apartment houses, senior citizen apartment houses, nursing homes and residential health-care facilities need a lot of at least 10,000 sq ft and 100 ft wide and at least 1,000 sq ft of lot per family, with a 1.20 floor area ratio and at most 3 stories and 35 ft.

  • The figures shown are for single- and two-family dwellings, with at least 2,500 sq ft of lot per family for a two-family dwelling and at least 5,000 sq ft for a single-family dwelling.
  • Those multifamily buildings keep a front yard of at least 25 ft, side yards of at least 25 ft and 50 ft, and a side front yard of at least 25 ft on a corner lot.
  • For single- and two-family dwellings, the 1.00 floor area ratio applies to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.67.
  • By special permit, a planned film and educational development follows the MG minimums except for 60% building coverage and a height of four stories or 60 ft, whichever is less.
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with at most 3 stories and 36 ft and a 1.00 floor area ratio.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).

Two-Family Dwellings - A single-family house needs at least 5,000 sq ft of lot, and a two-family house at least 2,500 sq ft of lot per unit.

  • The 1.00 floor area ratio applies to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.67.
  • On a corner lot, the side front yard is at least 10 ft.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width.
  • A planned cluster development needs a tract of at least 80,000 sq ft and lots of at least 2,500 sq ft, with 40% building coverage of the tract, and keeps the district FAR and lot area per family.
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Apartment Houses, High-Density - Apartment houses, senior citizen apartment houses, nursing homes and residential health-care facilities have a 3.00 floor area ratio, and their height may rise to 1 1/2 times the width of the street right-of-way they front.

  • The figures shown are for single- and two-family dwellings, with at least 2,500 sq ft of lot per family for a two-family dwelling and at least 5,000 sq ft for a single-family dwelling.
  • Those multifamily buildings keep a front yard of at least 25 ft, side yards of at least 16 ft and 32 ft, and a side front yard of at least 20 ft on a corner lot.
  • A nonresidential building follows the same height rule, and a building that fronts more than one street takes its height from the wider one.
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with a 1.25 floor area ratio.
  • For single- and two-family dwellings, the 1.00 floor area ratio applies to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.67.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).

Apartment Houses, Medium-Density - Apartment houses, senior citizen apartment houses, nursing homes and residential health-care facilities need at least 800 sq ft of lot per family and may reach 65 ft with no story limit, at a 1.25 floor area ratio.

  • The figures shown are for single- and two-family dwellings, with at least 2,500 sq ft of lot per family for a two-family dwelling and at least 5,000 sq ft for a single-family dwelling.
  • Those multifamily buildings keep a front yard of at least 15 ft, side yards of at least 12 ft and 25 ft, and a side front yard of at least 10 ft on a corner lot.
  • For single- and two-family dwellings, the 1.00 floor area ratio applies to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.67.
  • A nonresidential use needs a lot of at least 15,000 sq ft and at least 150 ft of width, with at most 3 stories and 36 ft and a 1.20 floor area ratio.
  • A detached one- or two-family dwelling must also meet a 45-degree side setback plane that begins 20 ft above each side setback line, with a 35 ft maximum exposed wall height (§ 43-34H).
  • On an existing lot narrower than 50 ft or shallower than 100 ft, the side and rear yards may be reduced, the rear yard never below 15 ft (§ 43-33K and L).

Planned Industrial, Residences Excluded - Buildings on one lot must stand at least 50 ft apart, and on a corner lot the side front yard is at least 50 ft.

  • A building or group of buildings with at least 70,000 sq ft of gross floor area is a planned mixed use development under § 43-36L.
  • By special permit, a planned executive park on a site of at least 30 acres becomes its own PEP district (§ 43-74D).

Planned Executive Park - Where the approving agency finds that taller buildings better protect the environment and the surrounding residential areas, a building may reach eight stories or 105 ft, whichever is less, within the approved floor area.

  • The City Council designates a planned executive park on a site of at least 30 acres in the OL, CM or IP districts after approval of a comprehensive development plan processed as a special use permit.
  • Business and commercial uses must stay at least 150 ft from any residential district line and within 16% of the park's floor area.
  • Parking stays at least 50 ft from residentially zoned property and at least 25 ft from streets.
  • Buildings stand at least 30 ft apart.

Neighborhood Business and Apartment Houses, Medium-Density - The figures shown are for single- and two-family dwellings. A nonresidential use may cover 70% of the lot at a 1.50 floor area ratio, with a front yard of at least 10 ft, a rear yard of at least 25 ft and a height of up to 35 ft.

  • A nonresidential side yard may be zero, but is at least 5 ft where the lot abuts a residential district.
  • In a building partly in residential use, coverage is 40% on every floor used in whole or in part for residences and 70% on floors used only for nonresidential uses.
  • Where only the first floor is nonresidential, the 70% coverage reaches no more than 20 ft above the street.
  • A building combining residential and nonresidential uses takes its floor area ratio from the formula in § 43-33M(2), never above 1.50.
  • Apartment houses, senior citizen apartment houses, nursing homes and residential health-care facilities have yards of at least 10 ft front and 16 ft and 32 ft side, and a 1.25 floor area ratio.
  • For single- and two-family dwellings, the 1.00 floor area ratio applies to the first 5,000 sq ft of lot; lot area beyond 5,000 sq ft counts at 0.67.

General Business and Apartment Houses, High-Density - Height for an apartment house or a nonresidential building may rise to 1 1/2 times the width of the street right-of-way it fronts, and the floor area ratio is 3.00 for apartment houses and 5.00 for nonresidential uses.

  • The figures shown are for single- and two-family dwellings, with at least 2,500 sq ft of lot per family for a two-family dwelling and at least 5,000 sq ft for a single-family dwelling.
  • Apartment houses, senior citizen apartment houses, nursing homes and residential health-care facilities keep yards of at least 10 ft front, 16 ft and 32 ft side and 20 ft rear.
  • A nonresidential use keeps a front yard of at least 10 ft and a rear yard of at least 20 ft and may cover 70% of the lot, and its side yard may be zero.
  • In a building partly in residential use, coverage is 40% on every floor used in whole or in part for residences and 70% on floors used only for nonresidential uses.
  • Where only the first floor is nonresidential, the 70% coverage reaches no more than 20 ft above the street.
  • An apartment house or nonresidential building that fronts more than one street takes its height from the wider one.

Restricted Business, Residences Excluded - Buildings on one lot must stand at least 40 ft apart, and on a corner lot the side front yard is at least 25 ft.

  • Height is set in feet only, with no story limit.

Central Business District - Buildings must be at least 2 stories or 25 ft tall, whichever is greater.

  • On a designated development site, coverage may reach 100%, height 400 ft and the floor area ratio 6.00, with no required rear yard.
  • Apartment houses follow the same coverage, height and floor area ratio, with at least 350 sq ft of gross floor area per apartment.

Downtown Waterfront District - Buildings must be at least 2 stories or 25 ft tall, whichever is greater.

Office Buildings and Research Laboratories, Residences Excluded - Buildings on one lot must stand at least 40 ft apart, and on a corner lot the side front yard is at least 25 ft.

  • By special permit, a planned executive park on a site of at least 30 acres in the OL, CM or IP districts becomes its own PEP district (§ 43-74D).

Wholesale Business and Storage - Height is not a fixed figure: a building may rise to 1 1/2 times the width of the street right-of-way it fronts, or of the wider street where it fronts more than one.

  • Residences are excluded from the first floor except in predominantly residential buildings (§ 43-11).

Commercial, Storage and Light Manufacturing, Residences Excluded - Buildings on one lot must stand at least 15 ft apart, and on a corner lot the side front yard is at least 20 ft.

  • By special permit, a planned executive park on a site of at least 30 acres becomes its own PEP district (§ 43-74D).
  • By special permit, a planned neighborhood commercial development in Shopping District 12 keeps a build-to line along at least half the principal street frontage (§ 43-74E).

Industry, Residences Excluded - Height is not a fixed figure: a building may rise to twice the width of the street right-of-way it fronts, or of the wider street where it fronts more than one.

Colleges, Universities and Theological Seminaries, Culture and Arts - Buildings on one lot must stand at least 20 ft apart, and on a corner lot the side front yard is at least 25 ft.

Government Center District - Buildings must be at least 2 stories or 25 ft tall, whichever is greater.

  • On a designated development site, no rear yard is required, coverage may reach 100% and height 220 ft.

Planned Multi-Use Development - Residential buildings and hotels may reach 16 stories or 180 ft, whichever is greater; nonresidential buildings other than hotels may reach 7 stories or 90 ft, whichever is greater. Heights are measured from the first-floor elevation.

  • Setbacks and other dimensions are those shown on the approved site plan, and setbacks, coverage and floor area ratio are measured treating the whole tract as one lot.
  • A mixed-use building counts as residential when at least 20% of its floor area at and above the first floor is residential.
  • A floor used only for parking or mechanical equipment is not a story, and parking floors, retail storage and open terraces are left out of floor area.

Ludlow Mixed-Use District - The 65 ft height may be exceeded where Map G allows; above 65 ft a building keeps an upper-story setback of at least 5 ft, and towers stand at least 60 ft apart with at most 12,000 sq ft (residential) or 20,000 sq ft (nonresidential) of footprint.

  • Buildings must be at least 25 ft and two stories tall.
  • A front setback is not required, but where one is provided it is 5 ft.
  • On Block 166 Lot 5 and Block 165 Lots 1, 30 and 31, a building that provides on-site commuter parking may reach 100 ft (§ 43-238C).

Artisans & Industry Special District - Height is not a fixed figure: a building may rise to twice the width of the street right-of-way it fronts, or of the wider street where it fronts more than one.

  • The district follows the dimensional regulations of the I district (§ 43-232).
  • The district covers Blocks 2071, 2073, 2179 and 2183 (§ 43-231).

Austin Avenue Special Shopping District - The district is developed as a single planned development under a comprehensive development plan approved by the City Council (§ 43-48B).

  • No building may stand within 10 ft of a public street or of the district boundary.
  • Buildings stand at least 5 ft apart, and parking stays at least 25 ft from any lot in residential use.

South Broadway District - Height and floor area ratio depend on the subdistrict: Central 40 ft and 4.0; Core 50 ft at the base and 80 ft in total, and 3.0; South and North 60 ft at the base and 120 ft in total, and 10.0.

  • Apartment houses are permitted only in the Core, South and North subdistricts, where residential uses keep a rear yard of at least 25 ft (§ 43-47E).
  • The 10 ft rear yard shown applies to commercial uses.
  • In the Core subdistrict, a tower sets back at least 15 ft above 50 ft.
  • New buildings meet the average build-to line of the adjacent buildings, and the ground floor facade must be 70% transparent.
  • A building portion above 50 ft or four stories, whichever is less, may be at most 100 ft wide along the frontage (§ 43-47C).

Mixed-Use District - In the Map B maximum height district, a building may reach 435 ft on a lot of one acre or more within 1/8 mile of the Yonkers Metro-North station, 300 ft on 1.5 acres or more between 1/8 and 1/3 mile, and 400 ft on four acres or more between 1/3 and 1/2 mile.

  • Buildings stand on a 0 ft build-to line at the front and side front, which may step back up to 25 ft for a public plaza or seating area beside a street.
  • Buildings must be at least 25 ft and two stories tall, and residential uses keep a rear setback of at least 10 ft.
  • Above 66 ft, a building keeps an upper-story setback of at least 5 ft, and towers stand at least 60 ft apart, limited to 12,000 sq ft (residential) or 20,000 sq ft (nonresidential) of footprint.
  • Near the Metro-North station, larger allowances apply for two to six towers (§ 43-221B).
  • A tract of 1.75 acres or more in the maximum height district may be designated a designated development site and treated as one lot (§ 43-46).
  • Map C adds sidewalk-width setbacks on some streets.

Downtown Industrial Research and Technology District - Residential uses are prohibited (§ 43-219B). Buildings stand on a 0 ft build-to line at the front and side front and must be at least 25 ft and two stories tall.

  • The build-to line may step back up to 25 ft for a public plaza or seating area beside a street, and Map C adds sidewalk-width setbacks on some streets.
  • The 66 ft height may be exceeded where the Map B height district allows, subject to the tower rules of § 43-221B.

Low Density Urban Residential District - The front setback is at least 5 ft and at most 20 ft, and each interior side setback is 10% of the lot width, at least 2.5 ft and never more than 5 ft required.

  • The figures shown are for a detached single-family dwelling, and a detached two-family dwelling has the same figures.
  • An attached two-family dwelling has interior side setbacks of at least 5 ft and a side front setback of at least 10 ft.
  • Townhouses need at least 20 ft of lot width per dwelling unit and never less than 70 ft, and their side setback of at least 5 ft applies only at the end of the development.
  • Dwellings must be at least 25 ft tall.
  • A corner lot needs a side front setback of at least 5 ft.
  • Nonresidential uses have a side front setback of at least 25 ft and no maximum front setback.

Medium Density Urban Residential District - The front setback is at least 5 ft and at most 20 ft, and each interior side setback is 10% of the lot width, at least 2.5 ft and never more than 5 ft required.

  • The figures shown are for a detached single-family dwelling, and a detached two-family dwelling has the same figures.
  • An attached two-family dwelling has interior side setbacks of at least 5 ft and a side front setback of at least 10 ft, and an apartment house one of at least 10 ft.
  • Townhouses need at least 20 ft of lot width per dwelling unit and never less than 70 ft, and their side setback of at least 5 ft applies only at the end of the development.
  • Dwellings must be at least 25 ft tall.
  • A corner lot needs a side front setback of at least 5 ft.
  • Nonresidential uses have a side front setback of at least 25 ft and no maximum front setback.

High Density Urban Residential District - The figures shown are for an apartment house, which stands on a 0 ft front build-to line unless Map C sets a sidewalk-width setback. Buildings must be at least 25 ft and two stories tall.

  • The 66 ft height may be exceeded where the Map B height district allows (§ 43-221B).
  • On a corner lot the same build-to rule holds for the side front, which runs only to the rear setback line.
  • Townhouses need a lot of at least 6,000 sq ft and at least 20 ft of lot width per dwelling unit, never less than 70 ft, and keep a front setback of 5 ft to 20 ft.
  • A townhouse's side setback of at least 5 ft applies only at the end of the development.
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Building a full house instead?

A standard-finish house in Yonkers runs $242–318/sq ft, about $435k–570k at 1,800 sq ft , plus roughly $66,728 for a conforming lot. See what it costs to build a house in Yonkers.

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
Bedford
800 sq ft ≈ $235k–310k

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

ADU cost in Yonkers: common questions

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

An 800 sq ft accessory dwelling unit in City of Yonkers 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 Yonkers?

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 Yonkers?

City of Yonkers has 34 districts. 24 of 34 districts prohibit ADUs. 10 districts have incomplete data - verify with the building department at (914) 377-6500. Check the specific address with the free ADU checker before you spend money on design.

Can I rent an ADU in Yonkers short term?

No local short-term-rental law on record - which is not the same as permission for City of Yonkers. 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 City of Yonkers 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) 377-6500 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.

Building outside these counties?

Aldo covers 15 New York counties today. Tell us your market and we'll build the zoning + feasibility data for it.