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More Information: Topography in the SNAD

Updated: May 5

This overview of SNAD regulations is provided for informational purposes only—the actual regulations are much more complex than this overview. Contact the Bronx Office of City Planning, at 718-220-8500, with your specific project plans and a description of your property, to ensure that you comply with all zoning requirements. City Planning will guide you through the approval and permitting process.


Topography (including steep slopes)


Modifications to a slope can affect storm water and groundwater drainage patterns, soil conditions, and vegetation health. In the SNAD, lots are characterized as:

  • Tier I - average slopes of < 10 %

  • Tier II - average slopes of 10 % or greater (includes "steep slopes")

  • steep slopes - slopes of 25 % or greater


Maximum Lot Coverage Lot Coverage is the portion of a zoning lot which, when viewed from above, is covered by a building or portion of a building. Slope Zoning District Permitted Maximum Lot Coverage steep slope R1, R2, R3 12.5 %

steep slope R4 20.0 %

10 - 14.9 % R1 - R4 varies from 22.5 to 36 %

15 - 19.9 % R1 - R4 varies from 20.0 to 32 %

20 - 24.9 % R1 - R4 varies from 17.5 to 28 %

Topography Category Grading Regulation Zoning Regulation

Projects that do not require Review by Department of City Planning Section 105-021, b

a building permit, such as required for changes to topography

some swimming pools, of more than two feet

garden sheds, or fences

Tier I Sites: Authorization from the City Planning Section 105-421

Projects that require a Commission required for any

building permit modification of existing topography.

Tier II sites: Authorization from the City Planning

Projects that require a Commission or any grading beyond 15 feet

building permit of the location of a building foundation

(Exception: driveways and private roads)

Grading within 15 feet of a foundation Section 105-34

Grading within 15 feet of a foundation

slopes, compaction of fill, retaining walls,

and other grading elements

Driveways and private roads Section 105-35

Topsoil is protected from erosion during construction:

"Any exposed earth shall have straw, jute matting , or geotextiles placed on it within two days of exposure and be seeded with annual rye grass during construction." (Section 105-36, (f))" "A development on a Tier II site, that needs an authorization, must inst


all one of the following erosion and sedimentation control measures: benches and berms, diversion channels, debris or sediment basins, retention ponds, or grassed waterways or outlets. (Sect. 105 -37)"




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