Can you build an ADU in Dobbs Ferry, NY?

One-Family Residential 1, One-Family Residential 2, One-Family Residential 3 - The minimum lot area is measured net, after the deductions in § 300-34A(2).

• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.
• The front yard is the lesser of the prevailing setback of the block face plus or minus 10 percent and the figure shown, and no building need stand more than 50 feet back from a street line.
• Height runs on roof pitch: 30 feet at a pitch of 0.25 or less, 33 feet above 0.25 up to 0.30, 35 feet above 0.30, and 28 feet to the eave, measured from the grade plane to the ridge.

Multifamily 1 - Each dwelling unit needs at least 6,000 sq ft of net lot area.

• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.
• Height runs on roof pitch: 30 feet at a pitch of 0.25 or less, 35 feet above 0.25 up to 0.30, 40 feet above 0.30, and 28 feet to the eave.

One-Family Residential 4, One-Family Residential 5, One-Family Residential 6 - The front yard is also capped at the prevailing setback, so it has a maximum as well as a minimum.

• The minimum lot area is measured net, after the deductions in § 300-34A(2).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.
• Height runs on roof pitch: 30 feet at a pitch of 0.25 or less, 33 feet above 0.25 up to 0.30, 35 feet above 0.30, and 28 feet to the eave, measured from the grade plane to the ridge.

Multifamily 2 - Each dwelling unit needs at least 3,500 sq ft of net lot area.

• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.
• Height runs on roof pitch: 30 feet at a pitch of 0.25 or less, 35 feet above 0.25 up to 0.30, 40 feet above 0.30, and 28 feet to the eave.

Mixed Density Residential 1 - Each dwelling unit needs at least 2,500 sq ft of net lot area.

• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.
• Height runs on roof pitch: 30 feet at a pitch of 0.25 or less, 33 feet above 0.25 up to 0.30, 35 feet above 0.30, and 28 feet to the eave, measured from the grade plane to the ridge.

Mixed Density Residential - Historic - Each dwelling unit needs at least 2,500 sq ft of net lot area.

• The code states no height in feet here, only the three-story limit.
• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.

Multifamily 3 - Each dwelling unit needs at least 2,500 sq ft of net lot area.

• The 40 foot height is set at a roof pitch of 0.25 or less, and no figure is stated for the steeper pitch bands.
• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.

Multifamily 4 - Each dwelling unit needs at least 1,750 sq ft of net lot area.

• Height runs on roof pitch: 35 feet at a pitch of 0.25 or less, 40 feet above 0.25 up to 0.30 and 42 feet above 0.30.
• No lot may be subdivided unless every resulting lot meets that figure (§ 300-35D(2)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.

Broadway - The front yard is the prevailing setback, the setback of the neighbouring buildings, rather than a fixed figure.

• Each dwelling unit needs at least 800 sq ft of net lot area.
• Height runs on roof pitch, measured from the curb: 40 feet at a pitch of 0.25 or less, 43 feet above 0.25 up to 0.30 and 45 feet above 0.30.
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.

Mixed Density Residential 2 - A third story must be set back 5 ft from the front of the building at ground level, measured within the first 40 ft of building width on a building wider than 40 ft.

• Each dwelling unit needs at least 800 sq ft of net lot area.
• On a building wider than 40 feet measured parallel to Palisade Street, the width beyond 40 feet takes another five feet of front yard (§ 300-35D(5)(c)).
• Net lot area is the gross area less half of any area with slopes of 25 percent or more and a quarter of any area sloping over 15 percent but under 25 percent (§ 300-34A(2)).
• The minimum lot area is the greater of the figure shown and the average lot area of the existing lots within 400 feet of the property, leaving out land in the OS-3 District (§ 300-35D(1)).
• On a lot of 7,500 square feet or more the building and impervious caps are multiplied by 0.82 up to 10,000 square feet, 0.75 up to 20,000, 0.67 up to 40,000 and 0.56 at 40,000 or more.
• Lot width and depth, the side yards and the front and rear yards are each the greater of the figure shown and a sliding scale, running on lot width for the sides and on lot depth for front and rear.

Downtown Business - A structure next to a residentially zoned property or the Old Croton Aqueduct must be set back at least 10 ft from that shared line, whatever the district minimum.

• The front yard also has a maximum, the prevailing setback.
• The side yard also has a maximum of 0 ft, which the Board of Trustees may waive to preserve light and air access or an existing driveway.
• The code sets no minimum lot area here and leaves the number of units to the developer, subject to the approval of the Board of Trustees.
• Residential use is prohibited along the whole ground floor of the principal building facing a public street, and that nonresidential space must be at least 25 feet deep (§ 300-36C(2)).
• A fourth story and height up to 45 feet may be granted only by the Board of Trustees through site plan review on a finding of public benefit, and its living area may not exceed half the story below.
• The district also sets a minimum of two stories and 24 feet.

Downtown Gateway - A structure next to a residentially zoned property or the Old Croton Aqueduct must be set back at least 10 ft from that shared line, whatever the district minimum.

• The code sets no minimum lot area here and leaves the number of units to the developer, subject to the approval of the Board of Trustees.
• Residential use is prohibited along the whole ground floor of the principal building facing a public street, and that nonresidential space must be at least 25 feet deep (§ 300-36C(2)).
• No maximum front yard is set for this district.
• No rear yard is required for a through lot in a downtown district where a court on a side lot line of at least the area of the required rear yard is provided instead (§ 300-34B(6)(b)).
• The district also sets a minimum of two stories and 24 feet.
• A fourth story and height up to 45 feet may be granted only by the Board of Trustees through site plan review on a finding of public benefit, and its living area may not exceed half the story below.

Downtown Transition - A structure next to a residentially zoned property or the Old Croton Aqueduct must be set back at least 10 ft from that shared line, whatever the district minimum.

• The front yard also has a maximum, the prevailing setback.
• The code sets no minimum lot area here and leaves the number of units to the developer, subject to the approval of the Board of Trustees.
• No rear yard is required for a through lot in a downtown district where a court on a side lot line of at least the area of the required rear yard is provided instead (§ 300-34B(6)(b)).
• The district also sets a minimum of two stories and 24 feet.
• A fourth story and height up to 40 feet may be granted only by the Board of Trustees through site plan review on a finding of public benefit, and its living area may not exceed half the story below.
• Cluster development is not permitted in the downtown districts.

Educational/Institutional - Residential use here requires rezoning to the underlying OF1 district, on Planning Board recommendation and Village Board of Trustees approval. Once converted, each dwelling unit needs at least 40,000 sq ft of lot.

• Coverage is calculated on net lot area, after open-space deductions.
• Density may be increased under the cluster development standards and the findings of site plan review (§ 300-37D(6)).
• The code publishes no minimum lot size for the district.
• Any redevelopment that subdivides property or puts up new structures must meet the cluster development standards of § 300-54F, and must carry a long-term plan for the site (§ 300-37D(2)).
• A 100,000 square foot lot with 60,000 square feet of open space may cover 20,000 square feet in buildings and 32,000 square feet in all.
• The footprint of an open parking deck counts against the impervious cap rather than the building cap.

Waterfront District A - The 150 ft front setback is measured from the mean high-water line of the Hudson River, and a variance can reduce it to no less than 100 ft.

• Side and rear yards are set at the Planning Board's discretion.
• No building may be longer than 150 ft in any one direction.
• The district permits no dwellings, and every use needs a special permit and site plan review.
• The exceptions to that permit requirement are restaurants, sales-oriented retail, artists and craftspersons studios and named educational enterprises in structures that existed on 23 September 2003.
• No part of a lot lying below the mean high water mark may be counted in working out yield, density, bulk, lot coverage or site coverage (§ 300-37A(5)).
• The setback does not bar a public walkway or esplanade, a seasonal kiosk or concession stand, a pier, dock, benches, picnic facilities, open recreational space or a footbridge.

Waterfront District B - Before bulk or density is worked out, an area equal to 140 percent of the footprint of any existing building or structure that is to remain is subtracted from the lot area, § 300-37B(3).

• Height is 45 ft or four stories, but no building may exceed 35 ft in height from the curbline on Palisade Street.
• Each dwelling unit needs at least 2,500 sq ft of gross lot area.
• The building and impervious caps are figured on gross lot area, not on the net area after open space deductions.
• The front, side and rear yards follow the MDR2 district's standards rather than figures of their own.

Chauncey Park - Each dwelling unit needs at least 1,800 sq ft of gross site area, and the Board of Trustees may raise the density by up to 20 percent in exchange for benefits such as open space, trails or traffic and transit improvements, § 300-37C.

• New construction must meet the cluster development standards of § 300-54F.
• Where clustering is proposed no front or side yard is required, but any front or side yard that is provided must be at least 10 ft.
• A yard of at least 10 ft must be left along any lot line bordering a residential district.
• The building and impervious caps are figured on gross lot area, not on the net area after open space deductions.

Open Space - The code establishes three open space districts, OS-1 Dedicated, OS-2 Reserved and OS-3 Reserved, § 300-30.

• Land in the OS-3 District is left out of the average lot area that sets a minimum lot area in the residential districts, § 300-35D(1).