North Carolina Wind Load Requirements

North Carolina Building Code Overview

North Carolina has adopted the 2018 North Carolina Residential Code, which establishes comprehensive wind load requirements for residential and commercial structures throughout the state. The code incorporates ASCE 7-16 (American Society of Civil Engineers Minimum Design Loads for Buildings and Other Structures) as the foundational standard for wind load calculations.

North Carolina's coastal location along the Atlantic Ocean exposes the state to hurricane-force winds, tropical storms, and severe coastal weather events. This unique exposure necessitates stringent wind design provisions, particularly in high wind counties such as Carteret, Dare, and Hyde, which are designated as Wind Zone III with design wind speeds of 110+ mph.

ASCE 7-16 Wind Load Standards

The 2018 North Carolina Residential Code references ASCE 7-16 for all wind load calculations. This standard provides methodologies for determining design wind pressures on both the Main Wind Force Resisting System (MWFRS) and Components and Cladding (C&C).

Wind Speed Determination

Design wind speeds in North Carolina are determined using the ASCE 7-16 wind speed maps, which provide ultimate design wind speeds (Vult) based on geographic location and risk category. Coastal counties experience significantly higher design wind speeds due to hurricane exposure:

• Coastal High Wind Counties: 110-140 mph (Wind Zone III)
• Central North Carolina: 90-110 mph (Wind Zone II)
• Western North Carolina: 85-100 mph (Wind Zone I)

North Carolina City Wind Load Guides

For detailed city-specific wind load requirements, building codes, and local enforcement information, explore our North Carolina city guides:

Components and Cladding (C&C) Requirements

Components and Cladding design is critical for North Carolina structures, particularly in coastal areas. C&C elements include windows, doors, roofing systems, siding, and other building envelope components that do not contribute to the structural frame. These elements experience higher localized wind pressures due to edge effects, corner zones, and discontinuities.

ASCE 7-16 provides specific pressure coefficients (GCp) for various C&C zones based on:

• Effective wind area of the component
• Location on the building (corner, edge, or field zone)
• Building height and exposure category
• Wind directionality

High Wind Zone Provisions (Chapter 45)

North Carolina's building code includes Chapter 45: High Wind Zone Provisions, which establishes enhanced requirements for construction in coastal counties exposed to hurricane-force winds. These provisions mandate specific construction techniques, material specifications, and engineering practices to ensure structural integrity during extreme wind events.

Wind-Borne Debris Regions

Coastal counties with design wind speeds of 130+ mph are designated as wind-borne debris regions. In these areas, windows, doors, and skylights must be protected with impact-resistant glazing or approved shutter systems. This requirement protects the building envelope from windborne projectiles, which can cause catastrophic pressure changes if breached.

ICC 600 Standard Compliance

North Carolina requires compliance with the ICC 600 Standard for Residential Construction in High-Wind Regions for structures located in zones with design wind speeds of 130-150 mph. ICC 600 provides prescriptive construction methods and engineered design approaches specifically tailored for high-wind residential construction.

The ICC 600 standard addresses:

• Prescriptive Design Tables: Simplified design tables for common residential configurations
• Roof-to-Wall Connections: Uplift resistance capacities for various connector types
• Wall-to-Foundation Connections: Hold-down forces and anchor bolt spacing
• Sheathing Attachment: Nail spacing and edge distance requirements
• Roof Covering: Enhanced fastening schedules for asphalt shingles and metal roofing

Professional Engineer (PE) Stamped Plans

North Carolina requires Professional Engineer (PE) stamped plans for structures located in high wind zones. A North Carolina-licensed Professional Engineer must review and seal all structural drawings, calculations, and specifications to verify compliance with the NC building code and ASCE 7-16 standards.

When PE Stamping is Required

• High Wind Counties: All structures in counties designated as Wind Zone III (110+ mph)
• Complex Structures: Buildings with irregular geometry, large openings, or unique architectural features
• Commercial Buildings: All commercial and multi-family structures regardless of location
• Essential Facilities: Risk Category III and IV structures (hospitals, fire stations, shelters)

PE-stamped plans provide assurance that the structure has been designed by a qualified professional and meets all applicable code requirements. The PE's seal signifies professional responsibility for the design and compliance with engineering standards.

North Carolina High Wind Counties

North Carolina's coastal counties are subject to the highest wind design requirements due to their exposure to Atlantic hurricanes. The following three counties are designated as Wind Zone III with design wind speeds of 110+ mph:

Design Considerations for Coastal North Carolina

Designing structures in coastal North Carolina requires careful attention to wind load analysis, continuous load path design, and envelope integrity. Builders and designers should consider the following best practices:

Continuous Load Path

A continuous load path transfers wind forces from the roof through the walls to the foundation. This path must be uninterrupted and adequately designed at all connection points. Common connection elements include:

• Hurricane straps or clips (roof-to-wall)
• Anchor bolts or hold-downs (wall-to-foundation)
• Sheathing nailing patterns (diaphragm action)
• Structural sheathing on walls (shear resistance)

Building Envelope Integrity

Maintaining envelope integrity during wind events prevents internal pressurization, which can dramatically increase uplift forces on the roof. Key strategies include:

• Impact-resistant windows and doors in debris regions
• Properly sealed roof and wall penetrations
• Enhanced garage door bracing or wind-rated doors
• Secondary water barriers under roofing

Roofing System Design

Roofing systems experience the highest wind pressures and must be designed accordingly. Enhanced attachment methods include:

• 6-nail asphalt shingle attachment (instead of 4-nail)
• Reduced roof sheathing nail spacing (6" o.c. at edges)
• Sealed or self-sealing shingles
• Enhanced underlayment attachment
• Metal roofing with concealed fasteners and high uplift ratings

Resources and Professional Assistance

For complex projects, high wind zones, or structures with unique design requirements, consulting with a North Carolina-licensed Professional Engineer is essential. A PE can provide accurate wind load calculations, structural design, and stamped plans that meet all state and local code requirements.

Additional resources include:

• North Carolina Department of Insurance: Building code resources and code interpretations
• ASCE 7-16: Available from the American Society of Civil Engineers
• ICC 600 Standard: Available from the International Code Council
• Local Building Departments: Jurisdiction-specific requirements and permit information

Understanding and complying with North Carolina's wind load requirements is essential for safe, durable construction in one of the nation's most hurricane-prone regions. By following the 2018 NC Residential Code, ASCE 7-16 standards, and ICC 600 provisions, builders and designers can create structures that withstand the state's challenging wind environment.