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

Jump To:

Policy Guidance

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.

In Fall 2017, the city hired Code Study, LLC, as the consultant for the Hillside Development study to develop recommendations for policy guidance and code changes. Their recommendations were released to the public in Spring 2019, followed by a 30-day comment period. City staff met with stakeholders and members of the public to address concerns with the initial document and draft alternative proposals. The draft report was updated to represent a broader approach to hillside development that combines Code Studio’s expertise with community input.

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. Transition Zones
  2. Pedestrian Access
  3. Measurement of Height
  4. Transparency
  5. Retaining Walls
  6. Blank Foundation Walls

Transition Zones

The Need: 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.

Proposals: 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.

Pedestrian Access

The Need: 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.

Proposals: Provide guidance on pedestrian accessway requirements from a public sidewalk to a site or to a building entry and regulate access through retaining walls located between the sidewalk and the building.

Measurement of Height

The Need: 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.

Proposals: Offer flexibility to the current method by introducing the Multiple Module method of measurement in order to encourage buildings to follow topography. Additionally, reversing the basement portion of TC-17-16 would be the simplest way to incentivize an active ground floor.


The Need: 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.

Proposals: One option for a proposed change would measure transparency from a building’s ground floor level rather than sidewalk. 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. The other option is to change the measurement area to 2’-12’ from sidewalk grade.

Retaining Walls

The Need: The UDO only restricts retaining walls to 10’ tall segments with 2’ setbacks when they are built within 30’ of a street or sidewalk. When adjacent to sidewalks, more guidelines may be necessary to ensure a quality public realm.

Proposals: Proposed solutions are divided into two categories; form & massing options and treatment options. Combined with more clearly defined retaining wall measurement techniques, this menu of strategies adds flexibility to requirements to create better design outcomes for the public realm.

Blank Foundation Walls

The Need: Current foundation wall regulations limit size to 5’ from grade when within 30 feet of any primary street. While this regulation is effective in limiting exposed blank foundation walls near the public realm, it is not flexible and does not encourage other mitigation strategies.

Proposals: The manual suggests dimensional criteria and set maximum for blank foundation walls, or performance-based criteria setting a maximum percentage of foundation wall that may be blank. For foundation walls exceeding these maximums, treatment options would be required.

The Guidelines for Hillside and Sloped-Site Development in Mixed-Use Districts Report is available for download and viewing.




Lead Department:
Planning and Zoning
Service Categories:
Urban Design CenterZoning