By Dr. Joseph L. Bobb, DSc, architect, construction engineer, lecturer
Vincentians will forever remember July 1, 2024, as we all witnessed the devastating effects of Hurricane Beryl that swept through the islands with the utmost disrespect for the sun, sea, and sauna.
Hurricane Beryl is the first category 4 hurricane to affect the islands since 1955. As a result, her demolition job of the Grenadines islands, in particular, is a spectacle to behold, and one from which we can learn. Hurricanes like Beryl hold no prisoners and spare no one nor structure from their wrath. They have no respect for paupers or the affluent, the educated or the not-so-educated, politicians or regular citizens.
Beryl can be referred to as the great equaliser. We witnessed first-hand in many locations the flattened or damaged structures, downed power lines, and damaged water infrastructure along with a host of other problems. It is important then for us to take heed and use this experience as rich information to prepare for the rest of the season and the years to come.
While we cannot prevent the passage of a storm, we can definitively do more to minimise the impact on our infrastructure and more importantly, our residential structures. However, there must be greater collaboration between all stakeholders who are involved in the design of structures, supply of materials, and construction processes.
I am almost certain the words I hear or read about after the passage of the storm will be only a nine-day talk, like many other issues, for some, and, for others, it may be the motivation needed for a different path forward.
Phrases and media depicting resilience, rising from the rubble like phoenixes, and rebuilding were used often in many different circles. However, our rebuilding process cannot be executed the same way that was done before, especially in circumstances where simple construction rules were not observed or followed for some structures.
While there may be an earnest need to rebuild, repair, and relocate, there must be careful considerations taken to ensure that we build, repair, and relocate to minimise the devastating effects of another hurricane. Therefore, I suggest three simple solutions that we can employ to reduce the damage that can be caused by hurricanes.
- Using hurricane straps (restraints)
A hurricane strap (restraint) is a metal connector that is designed to address the problem of damage due to wind pressures acting on the structures. In any windstorm, hurricanes included, the roof needs to be secured — this is due to the uplift, the same physics that allows an aircraft to fly. This runs counter to our intuition since we tend to think about roofs collapsing, not flying. The uplift is the main vulnerability of houses. These restraints are designed to withstand winds up to category 5 hurricanes and, in other instances, tornadoes. This is not a novel idea, because if we take trips to our national parks and look at the gazebo’s construction, we can see evidence of the use of hurricane metal straps that secure rafters to walls. Therefore, I am suggesting that every rafter or every other rafter be secured to the walls using metal straps. The metal straps are designed to withstand wind forces of up to 150-155 mph, a normal category 5 storm.
- Building inspection and maintenance
Oftentimes, as humans, we carry out our duties reactively instead of proactively. Once we fail to prepare we have prepared to fail. When preparation for a storm is touted, we often talk about having an adequate water supply for a week, felling overhanging trees, and stocking up on canned foods. However, I would also suggest that we carry out building inspections not before the passage of the storm but in advance.
I took the liberty to inspect some of the damaged structures and dislodged roofs and noticed a great deal of termite damage on roof elements such as rafters, top plates, sole plates, and studs in wooden structures. The presence of termite-ridden- lumber did not help during the passage of the storm. Instead, it made it easier for the storm to dislodge some of the roof structures throughout the country.
We have to ensure that lumber used from framing is always treated against termite damage and it would not hurt to perform termite treatment yearly. Termites such as the woodworm and the colloquially named “wood lice” thrive in damp conditions; the lumber we use in our construction is always subject to expansion and contraction according to the temperature in the building. Once your lumber becomes saturated with moisture, an ideal condition is present for termites to operate and weaken our structures. What may look sound outside to you can be structurally weak inside.
Sometimes, it only takes storms like Beryl to reveal the damage that was present in our structures. Eventually, the opportunity is present for our homes to become beautiful tombs from the outside with dead man’s bones inside, structurally. Therefore, treating for termites, insects, and fungi is an important step to take as part of our preparation to preserve the structural integrity of the lumber and the soundness of the structure when additional wind loads are affecting our structures.
- Fasteners and roof slopes
When fasteners are used to clad materials such as corrugated sheet metals and tiles, the rules for placing fasteners should be adhered to strictly. I know there are cost implications for this, but there will also be cost implications in the end, more expensive ones. Here are some rules to consider.
- At roof eaves and ridges, a fastener (roofing nail or roofing screw) must be placed at all corrugations.
- Fasteners must pass through the cladding material into the rafter and not just the lath boards
- Rafters must be adequately spaced centre-to-centre to facilitate the placing of fasteners.
One must also pay attention to the roof slope used in the construction of roofs. Because of our Caribbean conditions, flat roofs (between 0 and 10 degrees) should be avoided according to location. Steeper slopes such as 7 in 12 or around 30 degrees are ideal as roof slopes help to break wind speed. We cannot only give attention to aesthetics when building roofs, but we must also pay attention to structural integrity. Like many struggles in life, we only know how resilient we are in times of adversity, in like manner; we would only determine our structural integrity in adverse weather conditions, for example, hurricanes. In steeper slopes according to spans used, roofing structures can be supported by trusses, which aid in the response to wind loads imposed on the buildings.
Traditionally, we love to see long roof overhangs of up to two feet or more; however, the lengths only act as a catalyst for uplift when strong winds get under them. Uplift refers to a type of structural failure whereby the roofing component of a structure is physically displaced due to a strong wind. With enough space for uplift, winds will remove roof structures with longer overhangs than those with shorter ones. I suggest no more than 12 inches for overhang.
In addition to shortened eaves and the use of fasteners, I also suggest the use of parapet walls around our roofs. Parapet walls were historically used to prevent the spread of fires to roofs when a building becomes engulfed. Once the roof is set ablaze, one can consider the entire structure destroyed because the consumed material will cave in and set ablaze other elements that were not burning. Parapet walls are structures located at the roof’s edge and extend upwards. Sometimes they are used as decorative features around roof eaves, but they can help to maintain the structural integrity of our roofs by breaking wind speed in collaboration with shortened eaves. In essence, they do not provide enough space for the wind to produce uplift to remove roofing members.
In summary, please let me reiterate that as humans we cannot build to withstand the devastating effects of powerful storms. However, we can build to minimise the effects. Stakeholders must collaborate more to ensure that the effects are minimised. Giving attention to issues such as the use of metal restraints, the regular inspection of structures, and giving attention to the placing of faster and roof slopes are just some of the simple ways we can minimize the loads placed on our roofs during major storms like Hurricane Beryl. Let us rebuild with resilience and foresight, knowing that our efforts today will safeguard our communities tomorrow.
Stay strong, Vincentians. Our resilience will guide us through any storm.
By Dr. Joseph L. Bobb, DSc, architect, construction engineer, lecturer
