Wake County, NC | 110-120 mph Design Wind Speed | North Carolina State Building Code (IBC) | Research Triangle | Exposure B
Calculate Raleigh Wind Loads Now →Raleigh, the capital of North Carolina and the anchor city of the Research Triangle, is located in Wake County, North Carolina, and has moderate wind load requirements that account for its inland piedmont location and exposure to tropical systems, severe thunderstorms, and occasional tornadoes. North Carolina has adopted the North Carolina State Building Code which incorporates the International Building Code (IBC) with state-specific amendments. Design wind speeds for Risk Category II structures typically range from 110-120 mph (3-second gust) based on ASCE 7-22 wind speed maps.
These requirements exist because Raleigh experiences frequent severe weather including tropical system remnants from Atlantic hurricanes, severe thunderstorms with damaging straight-line winds, and occasional tornadoes. The city's inland piedmont location provides some protection from direct hurricane impacts, but tropical storms and hurricane remnants regularly track through the region bringing sustained high winds and heavy rainfall. The rapid growth of the Research Triangle region, including Raleigh, Durham, and Chapel Hill, has made proper wind load design increasingly critical for residential, commercial, and institutional buildings.
Design Wind Speed (Risk Category II): 110-120 mph (3-second gust, varies by location)
Design Wind Speed (Risk Category III): ~125-135 mph
Design Wind Speed (Risk Category IV): ~135-145 mph
Exposure Category: B (urban/suburban areas)
Building Code: North Carolina State Building Code (adopts IBC)
Wind Load Standard: ASCE 7-22 (current edition)
County: Wake County
Weather Risks: Tropical systems, hurricanes, severe thunderstorms, tornadoes
Raleigh's design wind speed of 110-120 mph for Risk Category II structures reflects the city's inland piedmont location and exposure to tropical weather systems and severe convective weather. While not subject to direct coastal hurricane impacts like Wilmington or the Outer Banks, Raleigh wind speed requirements account for:
Hurricane Fran in September 1996 was particularly significant for Raleigh, producing widespread power outages and structural damage despite making landfall near Cape Fear over 100 miles to the south. The storm demonstrated that even inland piedmont cities require robust wind load design. More recently, Hurricane Florence in 2018 brought sustained tropical storm force winds to the Raleigh area, causing extensive tree damage and power outages.
Calculating wind loads for Raleigh projects requires following ASCE 7-22 methodology as adopted by the North Carolina State Building Code. The fundamental velocity pressure equation is:
qz = 0.00256 Kz Kzt Kd Ke V²
For Raleigh with V = 115 mph (typical central Raleigh) and standard conditions, the resulting pressures are moderate. A Raleigh project with:
Results in a velocity pressure of approximately qz = 24.2 psf—moderate compared to coastal hurricane zones but higher than many inland regions with less tropical weather exposure.
For areas with significant topographic features (hills, ridges in the piedmont region), the topographic factor Kzt may exceed 1.0, requiring detailed topographic analysis per ASCE 7-22 Section 26.8.
North Carolina has adopted the North Carolina State Building Code which incorporates the International Building Code (IBC) with state-specific amendments. The North Carolina Department of Insurance (NCDOI) Office of State Fire Marshal administers the state building code.
Key Raleigh building code considerations:
You can access Raleigh building permits and requirements through the City of Raleigh Inspections Department or Wake County Planning & Development.
Raleigh projects must be classified into Risk Categories per ASCE 7-22 Table 1.5-1. Higher risk categories require increased design wind speeds:
| Risk Category | Raleigh Design Wind Speed | Building Types |
|---|---|---|
| Risk Category I | ~105-110 mph | Agricultural facilities, temporary structures, minor storage |
| Risk Category II | 110-120 mph | Residential, commercial, most standard occupancies |
| Risk Category III | ~125-135 mph | Schools, assembly >300, substantial hazardous materials |
| Risk Category IV | ~135-145 mph | Hospitals, fire stations, emergency shelters, EOCs |
Most of Raleigh qualifies as Exposure Category B due to dense urban and suburban development:
Exposure Category B (Urban/Suburban): The vast majority of Raleigh qualifies as Exposure B due to extensive urban and suburban development with numerous buildings, mature tree canopy, and other obstructions. Exposure B assumes urban and suburban areas with buildings having heights generally less than 30 feet extending more than 800 feet upwind. This applies to downtown Raleigh, North Hills, Research Triangle Park, and virtually all established neighborhoods throughout the metro area.
Raleigh's Urban Forest: Raleigh is known for its extensive tree canopy coverage throughout residential and commercial areas. This heavy vegetation combined with dense development firmly establishes Exposure B for the majority of the metropolitan area.
Engineering Judgment Required: In rare cases such as large cleared sites, airport areas (RDU International), or major hilltops with exposed terrain, Exposure C may apply. Professional engineering judgment is required for unusual conditions.
Raleigh's status as the anchor city of the Research Triangle region and a major technology hub creates unique wind load design considerations:
Research Triangle Park: The Research Triangle Park (RTP), located between Raleigh, Durham, and Chapel Hill, is one of the largest research parks in North America. The park contains numerous corporate headquarters, research facilities, and institutional buildings that often qualify as Risk Category II or III structures requiring careful wind load analysis. The mix of office buildings, laboratories, and data centers demands reliable wind load design to protect critical research and technology infrastructure.
University Facilities: Raleigh is home to North Carolina State University (NC State), a major research institution with extensive campus facilities. University buildings including classrooms, laboratories, dormitories, and assembly spaces often qualify as Risk Category III structures requiring higher design wind speeds. The growing campus infrastructure and ongoing construction projects require consistent application of current wind load standards.
Rapid Growth: Raleigh consistently ranks as one of the fastest-growing metropolitan areas in the United States. The rapid residential and commercial development across Wake County requires careful attention to wind load requirements, particularly for high-rise residential towers, office buildings, and mixed-use developments in downtown Raleigh and suburban centers.
Raleigh's wind load requirements are significantly influenced by the city's exposure to tropical systems and hurricane remnants:
Hurricane Fran (1996): Hurricane Fran made landfall near Cape Fear as a Category 3 hurricane and tracked inland through the Raleigh area with sustained winds of 60-80 mph and gusts exceeding 100 mph. The storm caused catastrophic damage across Wake County with over 1 million power outages, extensive tree damage, and structural failures. Fran demonstrated that even 100+ miles inland, tropical systems can produce hurricane-force winds and extensive damage.
Hurricane Floyd (1999): Hurricane Floyd tracked through central North Carolina producing widespread flooding and wind damage. While wind damage was less severe than Fran, Floyd demonstrated the ongoing vulnerability of the Raleigh area to tropical systems, particularly the flooding risks associated with slow-moving storms.
Hurricane Florence (2018): Florence made landfall near Wrightsville Beach and slowly tracked inland through North Carolina. Raleigh experienced sustained tropical storm force winds and extensive power outages. The slow movement of the storm resulted in prolonged wind exposure and demonstrated the importance of proper roof design and attachment.
Severe Thunderstorms and Tornadoes: Beyond tropical systems, Raleigh experiences frequent severe thunderstorms producing damaging straight-line winds, large hail, and occasional tornadoes. The April 2011 tornado outbreak produced multiple tornadoes across central North Carolina including Wake County, causing extensive damage to residential and commercial structures.
Raleigh zip codes span a large metropolitan area with relatively consistent wind speed requirements. Common Raleigh zip codes include:
The WindLoadCalc.com wind load calculator automatically applies the appropriate Raleigh wind speed based on your specific zip code or street address, accounting for local terrain conditions and exposure.
Wind load calculations for Raleigh building permits have varying PE requirements depending on building type and complexity:
North Carolina Professional Engineers must be licensed through the NC Board of Examiners for Engineers and Surveyors.
Engineers, architects, and contractors should reference these official resources for Raleigh wind load compliance:
The wind load calculator at WindLoadCalc.com automatically applies all Raleigh-specific requirements:
WindLoadCalc.com automatically handles all Raleigh-specific requirements including the 110-120 mph design velocity, Exposure Category B assignment, Risk Category adjustments, and component pressure coefficients. Simply enter your Raleigh project address or zip code for instant, accurate calculations.
Calculate Raleigh Wind Loads Now →Raleigh's wind load requirements differ significantly from coastal North Carolina hurricane zones:
| Requirement | Raleigh (Inland) | Coastal North Carolina |
|---|---|---|
| Design Wind Speed | 110-120 mph | 140-160 mph |
| Exposure Category | Primarily B (urban) | C or D required |
| Wind-Borne Debris | Not required | Impact protection required |
| Hurricane Impact Zone | Not applicable | Required compliance |
| Primary Risk | Tropical remnants, severe thunderstorms, tornadoes | Hurricanes, tropical storms |
While Raleigh does not face direct coastal hurricane impacts, the city's exposure to tropical system remnants, severe thunderstorms, and tornado risk requires rigorous wind load design appropriate for North Carolina's inland piedmont environment.
Raleigh is the anchor city of the Research Triangle metropolitan area spanning multiple counties. Wind load requirements for the broader Research Triangle region are generally consistent with Raleigh proper:
Engineers working across the Research Triangle metropolitan area should verify specific wind speeds and exposure categories for each project location, though most of the region maintains consistent 110-120 mph design velocities and Exposure B conditions.
WindLoadCalc.com provides instant, accurate wind load calculations for Raleigh projects. Our software automatically handles the 110-120 mph velocity range, Exposure B determination, and generates PE-ready reports for building permit submission.
Try Raleigh Wind Load Calculator →