Severe hurricanes have always been a formidable foe when they hit land. Most notably is the level of destruction left in their wake after they move on. Lives are often dependent on the design and quality of the structure they ride out the storm in so ensuring it can withstand great wind force as well as storm surge is important. With an increased focus on designing specifically for wind, which is considered the ultimate test for engineers, new construction methods, designs and materials have been very successful in creating hurricane-resistant structures that are now saving lives.
Location Makes a Difference
Where a structure is built and the direction it faces has much to do with how well it can withstand gale-force winds. Reviewing the terrain category measurement guide prior to construction will ensure the best placement possible.
Safety Begins With the Roof
During a hurricane, wind forces create an uplift which is why roofs are generally the first things to go during such a storm. Once a breach in the building envelope has occurred, the increase in the internal pressure causes structural failure. To counter such problems, two designs have emerged in recent years that are proving very effective. The first is the dome roof. In France, Category 5 hurricanes have been no problem for the dome homes in Solaleya. Their aerodynamic design and absence of properties that would allow the wind to catch and lift the edges of the roof are absent resulting in a lower drag.
An even better design is the monolithic dome that is cast as one piece. The single-form plan makes it look like an igloo, but the minimal surface area produces exceptional strength. It is also self-insulating because of the limited outer sphere.
A second option is the use of hip roofs which have been growing in popularity over the past few years. This type of roof is geometrically designed so it is lightweight, slopes in all four directions, is pitched at 25 to 30 degrees, has little or no overhang at the eaves , includes parapets and has ridge ventilators. These roofs perform extremely well compared to traditional gable roofs in gale force winds that accompany hurricanes. That’s because they’re aerodynamically designed in such a way as to support the top of the exterior walls.
In hurricane prone areas, the shape of the structure is the second most important factor in determining how well it will hold up in high winds. Compact, symmetrical, simple shapes will hold up the best. That means that circular, hexagonal and octagonal structures will hold up better than square. Squares will hold up better than rectangles. And, rectangles will hold up better than L-shaped buildings. It’s important to always be aware of the importance and implications of design decisions in order to minimize the destructive power of storms.
* Monolithic dome homes are considered some of the safest when it comes to hurricane-resistant structures.
* With dome homes the focus is on aerodynamic design and minimization to reduce drag, but that doesn’t mean they can be beautiful.
* Structures made of concrete reinforced with steel in a circular shape are considered the safest of all options.
* Storm surge and flooding often does more damage than high winds. Building on steel pilings is one way to eliminate the problem.
Other Elements That Matter
Hurricane force winds act on a structure from multiple angles. As a result, hurricane-resistant buildings are now designed to withstand lateral forces acting along both the length and width of the building. They also can withstand severe vertical uplift force as well as a downward vertical load path. The forces that act in all directions also act on every element and connection within the structure. Wind-resistant design depends on all of the combined factors as well as the quality of the materials and workmanship. Still, there are many factors that influence whether or not a building has vulnerabilities that can lead to structural failure during strong winds. Here are a few things to keep in mind.
* Windows and doors should be rated for high wind. The doors should open out instead of in and the windows should have hurricane-rated shutters. Some homes include shutters that don’t have to be revealed when not in use.
* At this home, storm shutters roll into the wall when not in use then are just pulled down into place when needed.
All components of the building envelope should be secured with hurricane rated fasteners and/or the best choice available. For example, screws are more secure than nails and bolts are more secure than screws. Additionally, the mechanical connections that attach roofs to walls, walls to floors and floors to foundations will help prevent homes from slipping off foundations and collapsing.
* Rafters are secured with hurricane fasteners.
* Even modular homes can be built with a hurricane rating.
* Steel piers and a stone foundation anchor the home making it resistant to gale force winds.
Construction materials are equally important. For instance, reinforced concrete is better than brick or rock, brick or rock is better than wood and wood is better than OSB or plywood covered in siding;
* Concrete and steel provide a solid, secure foundation from which the imagination can take flight.
* Brick combined with stone make a real statement and hold up extremely well during hurricane season.
* For those that elect to utilize wood products just remember that the larger the timber, the more solid the final product such as that pictured here. Actually, log homes can withstand hurricane force winds better than most other types of construction because of their interlocking joints.
Mother nature is nondiscriminatory. As such, there’s no way to hold back the power that drives hurricanes toward land. Trying to protect our vulnerable architecture with shutters and sandbags may appear to be a lost cause. However, there are structures that have already been built that can withstand the strongest winds imaginable as well as the storm surge, flying debris and flooding that often accompanies hurricanes. The ultimate goal of those focused on creating the best designs for hurricane resistant buildings is to provide the protection needed to improve peoples’ odds of survival while maintaining aesthetic appeal.