What it costs to build an ADU in Mount Kisco, NY

Conservation Development District - These lots sit inside a development site of at least 25 acres, with density capped at one dwelling per 1.25 acres of net lot area and at least 35% of the gross site kept as substantially contiguous open space.

• The site keeps buffers at least 200 ft deep from a major street, 100 ft from any other street, 200 ft from a public or quasi-public recreation use and 100 ft from any property line.
• No parking, loading or buildings may stand in those buffers.
• Each lot must be held in fee simple, and principal access must come directly from a major street (§ 110-7C(1)(c)).
• A Tier 3 solar energy facility by special permit needs a 25-acre parcel with frontage and access on a county or state road, 200 ft setbacks and buffers on every side, and 1% building coverage.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-7C(2)).
• Height is 2 1/2 stories or 35 ft, whichever is less.

Planned Residential Development District - The figures shown are for detached one- and two-family dwellings; the side yard is at least 20 ft from a single-family lot but at least 10 ft from a multifamily one.

• Attached one-family dwellings in a cluster, no more than two to a building, need a gross site of at least 2 acres and at least 15,000 sq ft of net area per unit.
• Senior housing other than assisted living, and multifamily dwellings, need a special permit and a gross lot of at least 2 acres, with height up to 52 ft and 65% development coverage.
• Those uses set back at least 30 ft from a residentially zoned lot and at least 10 ft from a nonresidentially zoned one, on a lot at least 100 ft wide and deep.
• They keep 20% of the gross site as open space, and buildings may be up to 150 ft long, or up to 575 ft for senior enriched or independent-living housing where the Planning Board allows it.
• A cluster of attached one-family dwellings keeps half the gross site as open space, at 35% development coverage, with principal buildings at least 30 ft apart.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-27.3C(4)).

Moderate-Density Multifamily District - The figures shown are for townhouses, garden apartments, multifamily dwellings, recreation uses and public buildings, and no building may be longer than 100 ft. A detached one-family dwelling needs at least 6,250 sq ft of net lot area, a detached two-family at least 10,000 sq ft.

• Two-family and multifamily dwellings are permitted only on a parcel with a gross site area of at least 10,000 sq ft (§ 110-12B(1)).
• A detached one-family dwelling is held to 40% development coverage and a detached two-family to 50%, each on a lot at least 50 ft wide with a front yard of at least 25 ft.
• For those detached dwellings, building coverage runs on a net-lot-area ladder, from 25% on a lot under 5,000 sq ft to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• Their side yards must be at least 10 ft on a lot 70 ft wide or more, 8 ft with 18 ft for both above 60 ft but under 70 ft wide, and 6 ft with 16 ft for both under 60 ft wide.
• Their rear yard must be at least 30 ft, dropping on a lot under 125 ft deep but never below 20 ft.
• The multifamily site keeps a buffer at least 10 ft deep next to a nonresidentially zoned lot and at least 25 ft next to a residence or a residentially zoned lot.

Medium-Density Multifamily District - Townhouses, garden apartments and other multifamily dwellings are permitted by right on a parcel with a gross site area of at least 40,000 sq ft, and by special permit on a smaller one, and need at least 4,500 sq ft of net lot area per dwelling unit.

• Those multifamily standards are 30% building and 60% development coverage, a lot at least 100 ft wide and deep, and buildings no longer than 125 ft.
• Their setbacks are at least 30 ft from a nonresidential, two-family or multifamily lot and at least 80 ft from a one-family lot.
• Their buffer must be at least 10 ft deep at the front and 20 ft at the rear and sides next to a nonresidential lot, 25 ft next to a two-family or multifamily lot, and 75 ft next to a one-family lot.
• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.

High-Density Multifamily Residence District - Townhouses, garden apartments and other multifamily dwellings are permitted by right on a parcel with a gross site area of at least 40,000 sq ft, and by special permit on a smaller one, and need at least 1,500 sq ft of net lot area per dwelling unit.

• Their height is six stories or 70 ft, whichever is less, with 30% building and 70% development coverage and no facade longer than 160 ft.
• Their lot must be at least 100 ft wide and deep, with setbacks of at least 30 ft on every side and a buffer at least 20 ft deep on the front, rear and sides.
• Two principal buildings must be at least their average height apart.
• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.

Low-Density One-Family Residence District - The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.

• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• Height is 2 1/2 stories or 35 ft, whichever is less.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-8C(2)).

Medium-Density One-Family Residence District - Building coverage is not a flat percentage: it runs on a net-lot-area ladder, 25% of a lot under 5,000 sq ft, then 1,250 sq ft plus 24% of the area over 5,000 sq ft, stepping down each 1,000 sq ft to 2,150 sq ft plus 20% of the area over 9,000 sq ft.

• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.
• Side yards must be at least 10 ft on a lot 70 ft wide or more, 8 ft with 18 ft for both on a lot more than 60 ft but less than 70 ft wide, and 6 ft with 16 ft for both under 60 ft wide.
• Height is 2 1/2 stories or 35 ft, whichever is less.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-10C(2)).

Moderate-Density One-Family Residence District - The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.

• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• Height is 2 1/2 stories or 35 ft, whichever is less.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-9C(2)).

One- and Two-Family Residence District - Side yards scale with lot width, from at least 10 ft each on a lot 70 ft wide or more down to 6 ft with 16 ft for both under 60 ft wide.

• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.
• A parcel used lawfully for commercial purposes on October 13, 1987, may continue that use as if it were a permitted principal use (§ 110-11D).
• Height is 2 1/2 stories or 35 ft, whichever is less.
• A place of religious worship or religious school by special permit is held to yards of at least 30 ft front, 50 ft side and 50 ft rear, with a buffer at least 20 ft deep all around (§ 110-11C(2)).

Central Business District - 1 - No yard is required against a nonresidential boundary, but side and rear yards must be at least 20 ft against a residential district boundary; no front yard is required in either case.

• A side or rear yard voluntarily provided against a nonresidential boundary must be at least 6 ft (§ 110-15C).
• Height is three stories or 40 ft, whichever is less.

Central Business District - 2 - No front, side or rear yard is required against a nonresidential boundary; against a residential boundary, side and rear yards must be at least 20 ft.

• A side or rear yard voluntarily provided against a nonresidential boundary must be at least 6 ft (§ 110-16C).
• Height is three stories or 40 ft, whichever is less.

Limited Commercial District - Against a residential boundary, side and rear yards must be at least 30 ft; the front yard stays at 20 ft.

• A buffer must be at least 20 ft deep at the front, and at the rear and sides at least 5 ft next to a nonresidential lot or at least 10 ft next to a residential lot (§ 110-19C).
• Height is 2 1/2 stories or 35 ft, whichever is less.

Neighborhood Commercial District - No side or rear yard is required against a nonresidential boundary (at least 6 ft if one is voluntarily provided), but both must be at least 20 ft against a residential boundary.

• A townhouse option needs a subdividable site of at least 7,500 sq ft and at least 2,500 sq ft of lot per unit (§ 110-18C).
• A townhouse needs a front yard of at least 20 ft and at most 30 ft, a rear yard of at least 25 ft and no side yard.
• Townhouse building coverage is 35% and development coverage 65%, on a lot at least 25 ft wide and 100 ft deep, with height of three stories or 35 ft.
• No more than six townhouse units may stand in a row, and each group must be at least 30 ft from any other lot, building, group of buildings or differently zoned lot.
• Next to a residential lot the buffer must be at least 10 ft deep on the front, side and rear.
• Height is three stories or 35 ft, whichever is less.

General Commercial District - Against a residential boundary, the front yard must be at least 20 ft and side and rear yards at least 50 ft.

• Against a nonresidential boundary, no rear yard is needed where buildings abut; a rear yard that is provided must be at least 10 ft.
• A building may be no more than 160 ft long (§ 110-25C).
• The buffer must be at least 10 ft deep at the front and sides; at the rear none is required where buildings abut, but one that is provided must be at least 10 ft.
• Height is three stories or 40 ft, whichever is less.

General Retail District - No side or rear yard is required against a nonresidential boundary (at least 6 ft if one is voluntarily provided), but both must be at least 30 ft against a residential boundary.

• The buffer must be at least 20 ft deep at the front, and at the rear and sides at least 5 ft next to a nonresidential lot, 25 ft next to a multifamily lot and 40 ft next to a one- or two-family lot.
• A structured parking building by special permit serving commonly owned contiguous lots in the GR and H districts may be 45 ft high, with no setback or buffer along the shared lot lines (§ 110-17D).
• That parking building may also exceed 30% building coverage where the Planning Board allows it.
• Height is two stories or 30 ft, whichever is less.

Cottage Office District - The figures shown are for a detached one-family dwelling. Every other permitted use, offices included, needs at least 10,000 sq ft of net lot area, yards of at least 30 ft front, 15 ft side and 30 ft rear, and 35% building and 60% development coverage.

• Those other uses keep a buffer at least 10 ft deep on the front, rear and sides (§ 110-22C(2)).
• Building coverage runs on a net-lot-area ladder, from 25% of a lot under 5,000 sq ft down to 2,150 sq ft plus 20% of the area over 9,000 sq ft.
• The front yard must be at least 30 ft on a lot 150 ft deep or more, and at least 25 ft on a shallower lot.
• The rear yard must be at least 30 ft on a lot 125 ft deep or more; on a shallower lot it drops 1 ft for every 2 1/2 ft of depth under 125 ft, but never below 20 ft.
• Side yards must be at least 10 ft on a lot 70 ft wide or more, 8 ft with 18 ft for both on a lot more than 60 ft but less than 70 ft wide, and 6 ft with 16 ft for both under 60 ft wide.
• A building that existed when § 110-22 took effect may be converted to office use, with all buildings covering no more than 20% of the lot and floor area growing by no more than 50% (§ 110-22E).

Low-Intensity Office District - Against a residential boundary, the side yard must be at least 25 ft; the front and rear yards are the same against either boundary type.

• A buffer at least 10 ft deep is required on the front, rear and sides (§ 110-21C).
• A parcel used lawfully for commercial purposes on October 12, 1987, may continue that use as if it were a permitted principal use (§ 110-21D).
• Height is 2 1/2 stories or 35 ft, whichever is less.

General Office District - Against a residential boundary, side and rear yards must be at least 50 ft; the front yard stays at 30 ft.

• A buffer at least 20 ft deep is required on the front, rear and sides (§ 110-20C).
• Height is three stories or 40 ft, whichever is less.

Research and Development District - The yards shown apply against a nonresidential boundary. Against a residential boundary, side and rear yards must be at least 35 ft, or at least 50 ft for a parking structure.

• A buffer at least 20 ft deep is required on the front, rear and sides (§ 110-23C).
• Height is three stories or 40 ft, whichever is less.

Light Manufacturing District - Against a residential boundary, side and rear yards must be at least 30 ft; the front yard stays at 10 ft.

• A buffer at least 10 ft deep is required on the front, rear and sides (§ 110-24C).
• Height is 2 1/2 stories or 35 ft, whichever is less.

Service Commercial District - Against a residential boundary, side and rear yards must be at least 30 ft; the front yard stays at 10 ft.

• A buffer at least 10 ft deep is required on the front, rear and sides (§ 110-24.1C).
• Height is 2 1/2 stories or 35 ft, whichever is less.

Hospital District - The figures shown are for a hospital, clinic, medical education or extended-care facility and every other permitted use, in a building of four stories or 48 ft or less. A taller building, up to 14 stories or 200 ft, needs Village Board approval after a public hearing.

• A building over 48 ft or four stories must set back at least 60 ft at the front and at least 120 ft at the sides and rear (§ 110-26C(2)).
• No part of a building above 48 ft may stand within 120 ft of a lot in separate ownership.
• That approval also needs a report from the Fire Chief and Village Engineer on water supply and pressure.
• Dwellings the hospital owns and operates, for its staff and their families or for families with a member over 62, need a special permit and at least 3,125 sq ft of net lot area per unit.
• Those dwellings are held to 25% building coverage, 2 1/2 stories or 35 ft, whichever is less, and facades no longer than 160 ft, on a lot at least 100 ft wide and deep with yards of at least 30 ft.
• A structured parking building by special permit serving commonly owned contiguous lots in the H and GR districts may be 45 ft high, with no setback or buffer along the shared lot lines (§ 110-26D).

Preservation District - A golf course or country club needs a special permit and a lot of at least 25 acres, with every building, parking and loading area at least 100 ft from any street or lot line.

• The district's principal uses are public parks and recreation areas, natural open space and public buildings.
• A cemetery by special permit keeps graves and structures at least 25 ft from any lot line (§ 110-6B(2)(b)).
• A Tier 3 solar energy system by special permit needs frontage and access on a county or state road and keeps all panels and structures at least 25 ft from any lot line.

Recreation District - The yards shown apply against a nonresidential lot; against a residential lot, side and rear yards must be at least 30 ft, while the front yard stays at 20 ft.

• The buffer must be at least 20 ft deep at the front, and at the rear and sides at least 5 ft next to a nonresidential lot, 20 ft next to a multifamily lot and 40 ft next to a one- or two-family lot.
• Height is two stories or 30 ft, whichever is less.

Mixed Use Residential and Commercial District - Along a lot line abutting a residential district the side and rear yards rise to at least 30 ft; the front yard stays at least 20 ft.

• Townhouses may be built instead on a gross site of at least 7,500 sq ft, which may be subdivided into fee simple lots of at least 2,500 sq ft per unit, 25 ft wide and 100 ft deep.
• Retail stores, personal service establishments and service establishments are permitted only on a lot of at least 10,000 sq ft, and restaurants only on a lot of at least 20,000 sq ft (§ 110-19.1B(1)).
• A buffer must be at least 20 ft deep at the front, and at the rear and sides at least 5 ft next to a nonresidential lot or at least 10 ft next to a residential lot.
• Townhouse building coverage is 35% and development coverage 65%, with height of three stories or 35 ft.
• A townhouse front yard runs from at least 20 ft to no more than 30 ft, the rear yard is at least 25 ft, and no side yard is required.
• No more than six townhouse units may stand in a row, and each group of six must be at least 30 ft from any other lot, building, group of buildings or differently zoned lot.