Building Height Measurement and Calculation in Raleigh, NC
Building height in the City of Raleigh is measured from the average post-development grade to the highest point of a pitched or flat roof. The Raleigh Unified Development Ordinance (UDO) utilizes several distinct methodologies—including the Single Building, Multiple Module, and Infill Development methods—to determine height based on site topography and the number of primary street frontages. Specific exemptions are provided for architectural features like spires and parapet walls, as well as for certain basement and attic configurations.
General Measurement Rules
In the City of Raleigh, building height is fundamentally calculated as the vertical distance from the average grade to the top of the highest point of the roof [Sec. 1.5.7.A.1]. This measurement applies to the entire building unless the developer utilizes the Multiple Module Height Method.
Average Grade Determination
The "average grade" used for height calculations depends on the chosen methodology:
- Single Building Height Method: The average grade is the average post-development grade above sea level measured along the building elevation that is most parallel and closest to the primary street setback [Sec. 1.5.7.A.2.a].
- Multiple Module Height Method: A building can be broken down into two or more modules. Each module has its own average grade based on the elevation of that specific module's wall plane most parallel and closest to the primary street [Sec. 1.5.7.A.2.b].
- Infill Development Height Method: For buildings subject to infill standards, the average grade is determined by averaging four specific points: the highest and lowest elevations of both the pre-development and post-development grades along the elevation closest to the primary street [Sec. 1.5.7.A.2.c].
Multiple Primary Streets
If a lot in the City of Raleigh is determined to have more than one primary street, the height must be calculated independently for each street. The maximum building height must be met from the average grade of each primary street elevation [Sec. 1.5.7.A.3].
Height Limits and Stories
Building height is often regulated by both a maximum number of stories and a maximum number of feet. In Mixed Use Districts, the height is designated by a suffix in the zoning code (e.g., CX-5 allows up to 5 stories) [Sec. 3.3.1.A].
Mixed Use District Height Designations
| Height Designation | Maximum Stories | Maximum Feet |
|---|---|---|
| -3 | 3 stories | 50 feet |
| -4 | 4 stories | 68 feet |
| -5 | 5 stories | 80 feet |
| -7 | 7 stories | Set by district |
| -12 | 12 stories | Set by district |
| -20 | 20 stories | Set by district |
| -30 | 30 stories | Set by district |
| -40 | 40 stories | Set by district |
[Section 3.3.1.A]
Story Height Calculations
- Measurement: Story height is measured from the top of a finished floor to the top of the finished floor above [Sec. 1.5.7.C.1].
- Ground Story: Minimum ground story heights typically apply to the first 30 feet of the building measured inward from the street-facing facade [Sec. 1.5.7.C.2].
- Mezzanines: A mezzanine is not considered a story if it comprises less than 50% of the floor area of the room in which it is located. If it exceeds 50%, it is counted as a story [Sec. 3.3.1.E].
Height Encroachments and Exceptions
The Raleigh UDO allows certain structures to exceed the established height limits of a district, provided they meet specific criteria.
Parapet Wall Encroachments
Parapet walls are allowed to exceed the maximum height limit based on the following scale:
| Building Height | Allowed Parapet Encroachment |
|---|---|
| 3-Story Building | 4 feet |
| Each Additional Story | +1 foot |
| Maximum Total Encroachment | 12 feet |
[Section 1.5.7.A.1]
Exempt Architectural and Accessory Features
- Architectural Features: Spires, belfries, cupolas, domes, bell towers, and monuments not intended for human occupancy are exempt from district height limits [Sec. 1.5.7.D.1].
- Standard Accessory Features: Chimneys, flues, flagpoles, solar panels, and wind turbines may exceed the height limit by up to 12 feet [Sec. 1.5.7.D.2].
- Large Accessory Features: Cooling towers, elevator penthouses, and tanks may exceed the height limit by 12 feet if they occupy no more than 25% of the roof area and are set back at least 10 feet from the roof edge [Sec. 1.5.7.D.3].
Special Topographical and Design Cases
Downward Sloping Lots
On lots that slope downward from the primary street, an additional story may be permitted on the lower portion of the lot. This applies to Detached or Attached houses, any building in the Downtown Mixed Use District, or buildings zoned for a maximum of three stories, provided the structure does not include a basement [Sec. 1.5.7.A.7].
Basements and Attics
- Basements: A level is considered a basement if 50% or more of its perimeter wall area is located below grade. The floor of this level must be entirely below finished grade [Sec. 1.5.7.A.6].
- Attics: In Detached or Attached houses, an attic does not count as a story if 50% or more of the attic floor area has a clear height of less than 7.5 feet [Sec. 1.5.7.A.5].
Sections Cited
- Section 1.5.7. Height
- Section 3.3.1. Applicability (Height Requirements)
- Section 3.3.2. Building Height Standards
- Section 12.2. Defined Terms