By Edgar Leonard, Contributor
The Virgin Islands, along with its sister regional countries, is a coastal location lying along the path of hurricanes developed off the coast of Africa, and is highly vulnerable to the damaging impact of the high/strong winds, heavy rain, and high surges associated with hurricanes.
Every year during hurricane season that runs officially between June 1 and November 30, there is a high probability that one or more islands in this hurricane path could be hit by a hurricane.
Consequently, the Virgin Islands must take action to prevent and mitigate the loss of life and extensive property damage that could result from a hurricane.
One action is to develop, implement enhance and enforce a national building code.
Building Performance Assessment
Hurricanes Irma and Maria, Category 5 hurricanes (157+ miles per hour), are the strongest in recorded history to hit the BVI. Well, they did more than just hit the BVI; they ravaged, battered and decimated the BVI. Thankfully and regrettably, only a few lives were lost.
Nonetheless, the two monster storms left a trail of significant property damages.
Therefore, post hurricane action require a building performance assessment (BPA) to determine how buildings and other facilities performed in these monster storms. The total building from roof to walls to foundation must be assessed. The category 5 hurricanes damaged scores of roofs.
Therefore, based on the findings of the BPA, as well as by observations, the new revised building code must focus urgently on roofing systems and prescribe how to strengthen how rafters are anchored to the bond beam and ridge. It must also prescribe the thickness of the sheathing and how it is attached to rafters and trusses.
Further, the building code must also prescribe how galvanize, shingles, tiles (clay, concrete) and other roof coverings are attached to the sheathing and to either rafters or trusses. Any roofing system must have the strength to resist high winds for which they were designed and uplifting force.
Winds flowing over the surface of a roof creates a negative pressure or uplifting force above the roof, along with a positive force or pressure below that pushes up on the roof.
This pulling and pushing force can result in a roof lifting off, if the resisting force is not strong enough. The behaviour of wind flowing over a roof is similar to the behavior of air flowing over the wing of an airplane and resulting in a lifting force.
Wall, and Wall Openings
Another focus that must be prescribed is the strength of walls, and wall openings (windows, doors, garage doors). The walls and wall openings must have the strength to resist the design wind load.
Moreover, the building code must also prescribe a continuous load path, that is, the roof system must be connected to the walls and walls must be connected to the foundation.
A broken load path will contribute to building damages, including roof uplift.
Additionally, the building code must also provide structurally sound and affordable options for covering wall openings, that is, plywood, shutter and other covering. Covering wall openings protect against wind and against damage from wind-borne debris.
Wind and Storm Surge
Moreover, the focus should not be only wind resistance but also on damages and threats from storm surges. No doubt global warming or climate change is contributing to sea level rise, example, Kiribati (formerly Gilbert Islands) in the Pacific.
A further area of concern should be flooding resulting from poor drainage design, blocking drainage channels, rain events larger than the capacity of drainage system, and poorly maintain drainage channels. For example, a system designed to convey the flow from a 25-year rain event may flood with a 100-year rain event.
Clearly, many BVI residents may not be able to afford to construct a home or building to resist the high winds from a Category 4 or 5 hurricane. Consequently, buildings designed to resist Category 3 hurricane may receive significant damages from Category 4 and 5.
In the VI, most residents use their homes as ride out shelters. As such, residents should consider building a safe
room within their homes.
A safe room is a room constructed to offer a higher level of protection than the rest of the building. Further, government needs to consider constructing Category 4 and 5 ride out domes in each district.
As a final note, residents need to heed the weather warnings from the Department of Disaster Management and other agencies to protect life and property.
Admittedly, nothing can guarantee absolute protection for life safety and property damages. Nevertheless, heeding the warnings and taking protective actions can save lives and protect property.
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