What it costs to build an ADU in Nyack, NY

Single-Family Residential-1 - Front and rear yards are formulas: the front is 20% of lot area divided by lot width and the rear is 30% of that quotient, so a 7,500-square-foot lot 50 ft wide owes 30 ft in front and 45 ft behind.

• The side yard shown is the floor of a larger rule, five feet or 10% of the lot width, whichever is greater, and the two side yards together must total 30% of the lot width.
• A one- or two-family dwelling's front yard need not exceed the average of the two adjacent existing dwellings where both stand within a hundred feet on the same street side, block and district.
• Every dwelling unit needs 1,500 sq ft of usable open space.
• Accessory buildings may cover 7% of the lot and are capped at 12 ft; no coverage cap is published for the house itself.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.

Single-Family Residential-2 - Front and rear yards are formulas: the front is 20% of lot area divided by lot width and the rear is 30% of that quotient, so a 5,000-square-foot lot fifty feet wide owes 20 ft in front and 30 ft behind.

• The side yard shown is the floor of a larger rule, five feet or 10% of the lot width, whichever is greater, and the two side yards together must total 30% of the lot width.
• A one- or two-family dwelling's front yard need not exceed the average of the two adjacent existing dwellings where both stand within a hundred feet on the same street side, block and district.
• Usable open space is 1,000 sq ft per dwelling unit.
• Accessory buildings may cover 7% of the lot and are capped at 12 ft; no coverage cap is published for the house itself.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.

Two-Family Residential - Front and rear yards are formulas: the front is 20% of lot area divided by lot width and the rear is 30% of that quotient, so a 7,500-square-foot lot 50 ft wide owes 30 ft in front and 45 ft behind.

• A two-family building needs 0.2296 acres on 75 ft of width with a 100 ft lot depth where the one-family row sets none, and its floor area per unit drops to 750 square feet.
• The side yard shown is the floor of a larger rule, five feet or 10% of the lot width, whichever is greater, and the two side yards together must total 30% of the lot width.
• A one- or two-family dwelling's front yard need not exceed the average of the two adjacent existing dwellings where both stand within a hundred feet on the same street side, block and district.
• Usable open space is 1,000 sq ft per dwelling unit for a house and 500 sq ft for each unit of a two-family building.
• Accessory buildings may cover 7% of the lot and are capped at 12 ft; no coverage cap is published for the principal building.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.

Multifamily Residential-1 - No building may run more than a hundred and sixty feet long, and each unit needs 360 square feet of usable open space. The 600 square foot minimum floor area drops to 450 for an efficiency.

• Where the side or rear of a lot abuts a district boundary, that yard takes the dimension the more restrictive of the two adjoining districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap.
• Accessory buildings are capped at twelve feet everywhere in the village.

Multifamily Residential-2 - Each yard is the figure shown or half the building height, whichever is greater, so at the fifty-foot ceiling the side yard rises from twenty to twenty-five feet; the front stays at thirty and the rear at twenty-five. No building may run more than a hundred and sixty feet long.

• At full height the twenty-foot combined side yard cannot be reconciled with two twenty-five-foot side yards, and the larger figures govern.
• Each unit needs 100 square feet of usable open space and 600 square feet of habitable floor area, or 450 for an efficiency.
• Where the side or rear of a lot abuts a district boundary, that yard takes the dimension the more restrictive of the two adjoining districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap.
• Accessory buildings are capped at twelve feet everywhere in the village.

Multifamily Residential-3 - No building may run more than a hundred and sixty feet long, and each unit needs 100 square feet of usable open space. The 600 square foot minimum floor area drops to 450 for an efficiency.

• For a federally or state-assisted housing development, the Planning Board may cut the parking requirement by up to half.
• Where the side or rear of a lot abuts a district boundary, that yard takes the dimension the more restrictive of the two adjoining districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap.
• Accessory buildings are capped at twelve feet everywhere in the village.

Downtown Mixed Use-1 - No lot area, lot width, street frontage, lot depth or front yard is required, so a building may sit on the street line on a lot of any size. A side or rear yard facing a residential district becomes 15 ft and must carry a landscaped buffer.

• Side yards are not required, but any side yard that is provided must be at least 5 ft.
• The rear yard is waived for the first storey or 17 ft, whichever is less, and is 15 ft above that.
• An adaptive reuse project may keep an existing building's nonconforming height, floor area and yards by special permit from the Planning Board, and its first four units need no off-street parking.
• Each unit needs 600 sq ft of habitable floor area, or 450 sq ft for an efficiency.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.

Downtown Mixed Use-2 - The 15 ft front setback is measured from the curbline, not the lot line or the right-of-way, and a building must step back a further 5 ft at a height of 32 ft. No lot area, width or depth is required, only 50 ft of street frontage.

• Side yards are not required, but any side yard that is provided must be at least 5 ft.
• The rear yard is waived for the first storey or 17 ft, whichever is less, and is 15 ft above that.
• A side or rear yard facing a residential district becomes 15 ft with a landscaped buffer.
• Each unit needs 600 sq ft of habitable floor area, or 450 sq ft for an efficiency.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.

Residential Mixed Use - On a lot at the 25 ft minimum width, side yards of 10 ft each leave 5 ft of building. No front yard is required, so a building may sit on the street line.

• On a lot of 15,000 square feet or more the Planning Board may raise the floor area ratio from 0.75 to 1.0 for a mixed use project, and add a third storey at 40 feet under LEED certification.
• Bulk is controlled by the floor area ratio and the density cap rather than by lot coverage, which is not published.
• Each unit needs 600 sq ft of habitable floor area, or 450 sq ft for an efficiency.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Accessory buildings are capped at 12 ft in height.

Office Mixed Use - No density cap is set here, so the floor area ratio and height are what limit the number of dwellings. No front yard is required, so a building may sit on the street line.

• Bulk is controlled by the floor area ratio rather than by lot coverage, which is not published.
• Each unit needs 600 sq ft of habitable floor area, or 450 sq ft for an efficiency.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap.
• Accessory buildings are capped at 12 ft in height.

Corridor Commercial - The front setback is a band, at least 15 ft and at most 25 ft from the street line, so a building set too far back breaks the rule too. On a lot of 40,000 sq ft or more the floor area ratio rises from 0.5 to 0.6 and a 45% building coverage cap applies.

• Side yards are not required, but any that is provided must be at least 5 ft, and one facing a residential district must be 15 ft with a landscaped buffer.
• The rear yard takes the same 15 ft buffer rule against a residential district.
• Fifty square feet of usable open space is required per dwelling unit, and no minimum dwelling unit size is set here.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Accessory buildings are capped at 12 ft in height.

Waterfront - On a property with water frontage the yards are measured from the mean high-water line, not the lot line, which can move the building envelope a long way on a tidal parcel. No lot area or rear yard is required, and the lot needs at least twenty-five feet of street frontage.

• No storey limit is set, so the thirty-five-foot height is the only vertical control.
• Each unit needs 600 square feet of habitable floor area, or 450 for an efficiency.
• Where the side or rear of a lot abuts a district boundary, that yard takes the dimension the more restrictive of the two adjoining districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one, and a parapet or cornice may exceed the cap by four feet.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap.
• Accessory buildings are capped at twelve feet everywhere in the village.

Manufacturing - No lot area is required, but a lot needs 50 ft of street frontage. No density cap is set, so floor area ratio and height are what limit the number of dwellings.

• Each dwelling unit needs 600 sq ft of habitable floor area, or 450 sq ft for an efficiency.
• By Board of Trustees special permit, an existing building in an adaptive reuse project may keep a height, floor area and yards outside these figures, treated as legal rather than nonconforming.
• An adaptive reuse project needs no new off-street parking for its commercial part.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap, and a parapet or cornice may exceed it by four feet.
• Accessory buildings are capped at 12 ft in height.

Hospital - Every structure must stand at least 15 ft from the street line, or 25 ft where it faces a street with one- or two-family houses on the opposite side. Height may rise 2 ft for each additional foot of setback from the surrounding streets, to a ceiling of six storeys or 72 ft.

• The 31% coverage figure printed for this district applies to accessory buildings only; there is no coverage cap on the hospital itself.
• No minimum dwelling unit size and no density limit are set here.
• Where a side or rear lot line abuts a district boundary, that yard takes the dimension the more restrictive of the two districts requires.
• Height is measured from existing grade to the midpoint of a peaked roof or the top of a flat or mansard one.
• Spires, chimneys, flagpoles, aerials, rooftop mechanical plant and solar collectors are exempt from the height cap, and a parapet or cornice may exceed it by four feet.
• Accessory buildings are capped at 12 ft in height.