Thirty Years After Hurricane Andrew Devastated Florida, Researchers Are Using a “Wall of Wind” to Design Safer Homes – but Storms Are Getting Even More Intense

When Hurricane Dorian hit the Bahamas, many less-well-constructed homes turned into shrapnel, creating another problem. Once a building fails, even nearby homes built to withstand higher winds are in trouble because of the flying debris. Our testing has shown how debris from one building, under continuous winds of 130-140 mph or more, can take out the next building, and then that takes out the next building.

Roofs are often that weakest link. A roof is subjected to uplift force during a storm, so wind hitting the surface of the building needs to be able to escape. When wind runs into objects in that path, it can cause damage.

New designs are improving how buildings stand up to extreme winds. For example, storms can create powerful vortices – winds that swirl almost like a corkscrew at a building’s edge – that can strip away roofing material and eventually lift the roof itself. One innovation uses a horizontal wind turbine along the edge of a roof to diffuse the wind and generate power at the same time, a double benefit.

The shape of buildings can also either create weaknesses or help deflect wind. You’ll notice that most modern high-rises avoid sharp corners. Testing shows that more trapezoidal or rounded edges can reduce wind pressures on buildings.

And better safety doesn’t have to be costly. One experiment showed how just US$250 in upgrades was the difference between a small, shed-size building standing up to a Category 3 storm – or not. Hurricane straps attach a roof truss to the perimeter of the house. Ring shank nails, which have threads around the shank to grasp the wood, can resist wind forces better than smooth nails. Hurricane shutters also block entry points where the wind can penetrate and trigger catastrophic failure.

Installation also matters, and helps explain why roofs that appear to meet building code requirements can still fail and go flying in hurricanes.

Experiments we conducted have shown how an edge system – the metal elements between walls and the roof – that is installed just half an inch too high or low can prematurely fail at low winds, even though the system was designed to withstand a Category 5 hurricane. Roofers installing asphalt shingles and roofing tiles may need to go beyond the current code when sealing edges to keep them from failing in a storm.

Expanding Testing: 200 mph Winds + Storm Surge
While engineers have been gaining knowledge through testing, the nature of storms is changing as the planet warms.

Warmer temperatures – fueled by increasing greenhouse gas emissions from human activities – enable the air to hold more moisture, and warmer oceans provide more energy to fuel hurricanes. Research shows that bigger and more intense storms that are heavier with water and moving more slowly are going to hammer the areas they hit with more wind, storm surge, flooding and debris.

Storms like these are why we’re working with eight other universities to design a new facility to test construction against 200 mph winds (322 km/h), with a water basin to test the impact of storm surge up to 20 feet (6 meters) high plus waves.

Computers can model the results, but their models still need to be verified by physical experiments. By combining wind, storm surge and wave action, we’ll be able to see the entire hurricane and how all those components interact to affect people and the built environment.

Disaster testing is finding ways to make homes safer, but it’s up to homeowners to make sure they know their structures’ weaknesses. After all, for most people, their home is their most valuable asset.

Richard Olson is Director of the Extreme Events Institute, Florida International University. Ameyu B. Tolera isResearch Assistant at Florida International University - College of Engineering & Computing, Florida International University. This article was updated Aug. 24, 2022, to mark the 30th anniversary of Hurricane Andrew, and it is published courtesy of The Conversation.