RAS Engineering is a professional engineering company serving building managers and owners by providing advice, oversight restoration, and testing to ensure that all components of a build’s exterior and structure meet the standards necessary to provide quality durability and safe protection against the elements.
Hurricane Damage Assessment on
Non-Load-Bearing Walls and Wall Coverings
Masonry Veneer is a popular choice for building exteriors, but it presents some significant risks during high wind events. Veneers that aren’t properly tied to the structural backing are prone to collapse during storms. The guidelines emphasize that older buildings, built before more stringent building codes were introduced, are especially susceptible. Key signs of vulnerability include deteriorating mortar joints, corroded ties, and cracks in the veneer.
Assessment Strategy:
• Level 1 assessments involve basic visual inspections, checking for obvious signs of deterioration.
• Level 2 assessments dive deeper, using methods like borehole testing to inspect the cavities behind veneer walls for structural weaknesses.
Concrete Masonry Units (CMU) are another popular material for non-load-bearing walls. While durable, these walls can still fail under extreme wind pressures, particularly if there are weaknesses in the connections or the unit isn’t properly sealed against water infiltration.
Fiber Cement, Vinyl, and Wood Siding are also common exterior finishes, each with its own vulnerabilities. Fiber cement, though durable, can blow off if not properly nailed. Vinyl siding is often installed with gaps that allow wind to lift and damage large sections of a wall. To mitigate these issues, contractors are advised to use face nailing techniques for better fastening in high-wind areas.
The Hidden Weakness: Soffits
Soffits, which cover the underside of roof overhangs, are often overlooked but play a critical role in protecting a building during windstorms. They are highly susceptible to being ripped off in high winds, leading to wind-driven rain entering the attic and causing extensive interior damage.
The guidelines suggest ensuring soffits are securely fastened and constructed with vent covers to prevent wind-driven rain from entering the structure. Level 1 assessments include inspecting soffit panels for visible signs of damage or improper installation, while Level 2 assessments look deeper into how the soffits are framed and fastened to the structure.
Roof Systems: The Frontline of Wind Defense
Roof systems are one of the most critical areas to assess during a wind vulnerability evaluation. Roof failures are the leading cause of wind-related building damage and can lead to catastrophic internal damage from rainwater intrusion. The guidelines discuss various types of roofs, from membrane systems to asphalt shingles and metal panels.
Membrane Roofs—whether single-ply or multi-layered—are prone to uplift and punctures during strong wind events. Loose or improperly fastened edges can cause progressive failure across the roof. Inspections should focus on vulnerable areas such as corners and seams, which are most susceptible to uplift forces. The guidelines suggest using uplift testing to ensure that the roof can handle wind pressures, especially in areas where wind speeds exceed 120 mph.
Asphalt Shingles, another popular roofing option, face problems like unsealed tabs or weak starter courses, which make them prone to blow-offs. Inspectors are advised to perform spot checks in key areas like roof perimeters and ridgelines, where wind forces are strongest.
Metal Panels and Tiles are often seen as more resilient, but they too have vulnerabilities. Improper fastener spacing or poor attachment to the structural frame can cause these systems to fail. Regular inspections of fastener placement and tile condition are recommended to prevent wind-driven progressive failures.
Recommendations for Wind Mitigation
Based on the findings from these assessments, the guidelines offer several best practices for building owners and building managers:
• Inspect regularly: Regular visual inspections, particularly after storms, can help catch small issues before they become significant vulnerabilities.
• Focus on fastenings: Many wind-vulnerabilities stem from poor fastening techniques. Ensure that all components—whether roof systems, wall coverings, or soffits—are securely fastened according to modern standards.
• Upgrade outdated systems: For older buildings, especially those built before more stringent wind codes were adopted, consider retrofitting with wind-resistant materials or even constructing new facilities that meet current wind load standards.
• Document and prioritize: Use assessment findings to prioritize repairs and upgrades, focusing on the most critical vulnerabilities first.
Conclusion
Understanding and assessing the wind vulnerabilities of building components such as non-load-bearing walls, soffits, and roof systems are key steps in ensuring the continued operation of these essential buildings during and after severe wind events. By following the guidelines and performing thorough inspections, building managers and engineers can mitigate the risks posed by wind, protect building occupants, and reduce downtime in the event of a storm.