Guidelines for Hillside and Sloped-Site Development in Mixed-Use Districts

Last updated Jun. 04, 2019 - 9:23 am
Hillside Development

In 2015, the City of Raleigh adopted the Unified Development Ordinance (UDO) to establish standards for residential and commercial development. Updates to the UDO occur periodically when regulations need clarification or revision in order to achieve policy goals. One such area in need of improvement is how the UDO addresses sites with topography for commercial and mixed-use projects. Sloping terrain presents unique challenges for the design and development community, which the UDO does not adequately address.

Policy Guidance

The proposed policy guidance--included in the upcoming Guidelines for Hillside and Sloped Site Development in Mixed-Use Districts--fall into six general categories.

  1. Measurement of Height
  2. Pedestrian Access
  3. Neighborhood Transitions
  4. Transparency and Blank Wall
  5. Retaining Walls
  6. Base Dimensional Standards and Frontage

Measurement of Height

Problem: The UDO regulates building height with stories and height limits. Developments are incentivized to flatten sloped sites, thereby maximizing the size of each allowed story, instead of stepping a building up or down with topography.

Solution: Offer flexibility to the current method in order to encourage buildings to follow topography.

Pedestrian Access

Problem: Raleigh is a growing and urbanizing city, and it is a priority to enhance and enable pedestrian access and connectivity, particularly in areas with topography. Current regulations do not address all instances where safe and direct pedestrian access from the public sidewalk to a building entry is desired.

Solution: Provide guidance on pedestrian accessway requirements from a public sidewalk to building entry, with specific recommendations based on the type of building (Base Dimensional Standards) and context (Frontage).

Neighborhood Transitions

Problem: Part of the UDO provides guidance on how to mitigate the transition between residential and commercial areas by restricting the maximum building height in the transition area (Zone C) to 40 feet. In some cases, it has not been clear that the 40 feet height limit was intended to apply to not just buildings, but all structures in the Zone C. This lack of clarity has resulted in some unintended consequences.

Solution: The proposed language clarifies that no structure in the Zone C transition area can be more than 40 feet in height, as measured from pre-development grade.

Transparency and Blank Wall

Problem (Transparency): The UDO requires that all non-residential development includes a minimum percentage of transparency (e.g., windows), with a certain amount of this transparency present within the first twelve feet at any point along the building face. This transparency is currently measured from the sidewalk. Because no site is perfectly flat, this method is awkward for both designers to comply with as well as city staff to evaluate.

Solution (Transparency): The proposed change would measure transparency from a building’s ground floor level. This is a more common-sense approach to transparency measurement as it relieves pressures to create awkward solutions to conform to UDO requirements and creates a more objective evaluation system.

Problem (Blank Wall): The current UDO language is not clear on how the blank wall area is calculated. This is confusing for both designers and staff to evaluate. Additionally, the UDO does not address or propose strategies for large expanses of foundation walls.

Solution (Blank Wall): The manual proposes a dimensional standard to clarify blank wall as being any surface larger than 8’ in both height and width. Additionally, the manual clarifies what counts as a blank foundation wall and proposes acceptable treatments.

Retaining Walls

Problem: The UDO only restricts retaining walls to 10’ tall segments with 2’ setbacks when they are built within 30’ of a street or sidewalk. These regulations have resulted in excessively tall and overbearing retaining walls next to public sidewalks or neighboring property lines.

Solution: The manual encourages a more pedestrian scale for retaining walls, by limiting segments to 8’ tall and requiring deeper setbacks with planting requirements.

Base Dimensional Standards and Frontage

*Pedestrian Access requirements that are specific to building type or context can be found in this section.

A draft document is available for download and viewing. A 30-day comment period, from April 25 to May 24th, has been completed. Please send any questions to Allison Evans at

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