What it costs to build an ADU in Harrison, NY

One-Family Residence District - No lot in Blocks 591, 592, 601, 603 and 604 may be less than 200 ft wide, and on those lots the front yard is 50 ft and the side yards are 50 ft.

• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.
• A cluster subdivision needs Planning Board approval on a parcel of at least five acres, and no clustered lot may be smaller than half an acre, § 235-10.1.
• A senior living facility is a special exception use on a site of at least six acres with at least 1,500 ft of frontage on an arterial road, at up to 25 units per acre, § 235-17Z.
• Under that special exception the lot must be at least 800 ft wide, and coverage is capped at 20 percent and height at 55 ft or four stories.
• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 40 ft.

One-Family Residence District, One-Family Residence District - Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.

• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 30 ft.
• An accessory building may be 15 ft tall and, in a required rear yard, must stand at least 10 ft from the property line.
• On a lot in a floodplain the building height is measured from the base flood elevation.

One-Family Residence District - The Planning Board may permit a cluster subdivision on a parcel of at least five acres. No clustered lot may be smaller than half an acre, and the number of homes may not exceed what a conventional subdivision would yield.

• In a cluster approval the lot size, width, front yard and side yard may be varied, § 235-10.2.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.
• A senior living facility is a special exception use on a site of at least six acres with at least 1,500 ft of frontage on an arterial road, at up to 25 units per acre, § 235-17Z.
• Under that special exception the lot must be at least 800 ft wide, and coverage is capped at 20 percent and height at 55 ft or four stories.
• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 50 ft.

One-Family Residence District - The Planning Board may permit a cluster subdivision on a parcel of at least five acres. No clustered lot may be smaller than half an acre, and the number of homes may not exceed what a conventional subdivision would yield.

• In a cluster approval the lot size, width, front yard and side yard may be varied, § 235-10.2.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.
• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 50 ft.
• An accessory building may be 15 ft tall and, in a required rear yard, must stand at least 50 ft from the property line.

One-Family Residence District - The 50 ft setback from streams and other water bodies does not apply in this district, but a building permit on a lot holding or bounded by a stream goes to the Town Engineer for a recommendation.

• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 15 ft.
• An accessory building may be 15 ft tall and, in a required rear yard, must stand at least 10 ft from the property line.
• On a lot in a floodplain the building height is measured from the base flood elevation.

One-Family Residence District - Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.

• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 15 ft.
• An accessory building may be 15 ft tall and, in a required rear yard, must stand at least 5 ft from the property line.
• On a lot in a floodplain the building height is measured from the base flood elevation.

Two-Family Residence District - The 2,400 sq ft habitable floor area is the figure for two dwelling units; a one-family dwelling needs at least 800 sq ft.

• Height is measured from two ft above the lowest floor to the midpoint of the roof, flat roofs are not allowed, and the lowest level is never counted as a story, § 235-33.3.
• All area under a roof is measured at the outermost exterior wall and counts toward lot coverage in this district.
• On a lot in a floodplain the height rises to 33 ft with 2 1/2 stories of habitable space, and the area below the first floor is not a story.
• The lot width at the front lot line must be at least 75 percent of the required width measured at the front yard depth, and never less than 50 ft, § 235-33.
• On a corner lot, the yard along the side street must be at least 8 ft.
• An accessory building may be 15 ft tall and, in a required rear yard, must stand at least 5 ft from the property line.

Garden Apartment District - Between main buildings in a group there must be at least 30 ft or two thirds the height of the taller building, whichever is greater, and that distance need not exceed 35 ft where the top of one building is less than eight ft above the first floor level of the other.

• Usable open space of 200 sq ft per dwelling unit must be provided on the site, with no dimension less than 15 ft, and a park fee is payable to the town, § 235-25.
• The same spacing applies between a main building and a major detached accessory building, § 235-22.
• The 600 sq ft habitable floor area is per dwelling unit.
• A one-family dwelling is not a permitted use in GA.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.
• On a corner lot, the yard along the side street must be at least 30 ft.

Multifamily Residence District - Between main buildings in a group there must be at least 30 ft or two thirds the height of the taller building, whichever is greater, § 235-22.

• Usable open space of 200 sq ft per dwelling unit must be provided on the site, with no dimension less than 15 ft, and a park fee is payable to the town, § 235-25.
• The 600 sq ft habitable floor area is per dwelling unit, and a one-family dwelling needs 1,200 sq ft.
• One-family, two-family and multiple dwellings are all permitted here.
• A permitted use or structure may extend into an adjoining B district under single ownership only for parking, required yards, accessory recreation or open space, § 235-7I.
• On a corner lot, the yard along the side street must be at least 15 ft.
• The 50 ft setback from streams and other water bodies does not apply in this district, § 235-31.

Multifamily Limited Retail District - Beside a business district no side yard is required, and any side yard that is provided must be at least 10 ft; the 20 ft side yard applies where the lot adjoins a residence district.

• The minimum lot is 4,000 sq ft and the minimum lot area per family unit is 750 sq ft.
• No front yard is required.
• A six foot stockade fence or its equal is required along a side or rear line with a residence district; the Planning Board may waive or modify it where terrain or planting gives the same screening.
• Usable open space of 200 sq ft per dwelling unit must be provided for multiple dwellings, § 235-25.
• One-family, two-family and multiple dwellings and dwelling units over first floor nonresidential space are all permitted uses here.
• The 50 ft setback from streams and other water bodies does not apply in this district, § 235-31.

Central Business District - Beside a business district no side yard is required, and any side yard that is provided must be at least 10 ft; the 20 ft side yard applies where the lot adjoins a residence district.

• Dwelling units over first floor nonresidential space need a special exception.
• There is no minimum lot area, no minimum lot area per family unit and no front yard requirement.
• This district has no building coverage limit and no floor area ratio.
• A height restriction is measured from the average established curb grade on Mamaroneck Avenue.
• An off-street parking area needs a 10 ft setback, which must include a continuous landscaped strip at least 5 ft wide, except at access points, § 235-24F.
• A six foot stockade fence or its equal is required along a side or rear line with a residence district; the Planning Board may waive or modify it where terrain or planting gives the same screening.

General Commercial District - The 20 ft side yard applies only beside a residence district; beside a business district there is no requirement at all.

• A 15 ft landscaped setback is required along Osborn Road, closed to parking or storage of vehicles, and the Planning Board may reduce it where a visually impervious landscape buffer replaces it.
• Dwellings are not permitted except for dwelling units over first floor nonresidential space, which need a special exception.
• There is no minimum lot area and no minimum lot area per family unit.
• No coverage limit is set for multiple dwellings.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.

Neighborhood Business District - A multiple dwelling is a special exception use, and within 1,500 linear ft of the closest point of the Harrison Metro-North train station its height is 45 ft and four stories, or 40 ft and three stories on Halstead Avenue, § 235-17V.

• Beside a business district no side yard is required, and any side yard that is provided must be at least 10 ft; the 20 ft side yard applies where the lot adjoins a residence district.
• Under that special exception a multiple dwelling may cover up to 50 percent of the lot.
• Usable open space for a multiple dwelling is set by the Planning Board in site plan approval rather than at 200 sq ft per unit.
• There is no minimum lot area, no minimum lot area per family unit and no front yard requirement.
• An off-street parking area needs a 10 ft setback, which must include a continuous landscaped strip at least 5 ft wide, except at access points, § 235-24F.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.

Professional Business District - Beside a business district no side yard is required, and any side yard that is provided must be at least 10 ft; the 20 ft side yard applies where the lot adjoins a residence district.

• A multiple dwelling is not permitted here, only dwelling units over first floor nonresidential space, by special exception.
• There is no minimum lot area, no minimum lot area per family unit and no front yard requirement.
• This district has no building coverage limit and no floor area ratio.
• An off-street parking area needs a 10 ft setback, which must include a continuous landscaped strip at least 5 ft wide, except at access points, § 235-24F.
• A six foot stockade fence or its equal is required along a side or rear line with a residence district; the Planning Board may waive or modify it where terrain or planting gives the same screening.
• Buildings and structures must be set back 50 ft from the seasonal high water level or established channel line of a stream or other water body, § 235-31.