The end of August marked the 24 anniversary of Hurricane Andrew slamming into South Florida, and it’ll be 27 years this month since Hurricane Hugo ripped into the South Carolina lowcountry. Both events caused significant damage and more importantly, loss of life.
Just another hurricane season in Paradise, right.
The vernacular architecture of the lowcountry, and southern coastal regions in general, developed as a response to the heat, humidity and storms typical of our region.
As building science and technology have advanced, there are more improved ways of building your coastal home to withstand severe weather events like floods and hurricanes. Here’s the 5 strategies for building not just a beautiful home, but one that is also a flood and hurricane resistant one.
1. Don’t let it blow away.
Aside from the necessary structural engineering, the shape and configuration of your home can actually have an influence on whether or not it stays put in a hurricane.
For example, studies have been done on what shape house, what type of wall construction, and which type of roof bests performs in extreme weather conditions.
Square houses were found to be the sturdiest shape for high winds, while rectangular configurations with length to width ratios of 1:3 or less are also perform well. Week spots are typically created at inside corners.
Reinforce concrete block walls outperform other wall construction methods, but properly engineered wood-framed structures also perform well.
Hipped roofs with an angle of approximately 30 degrees outperformed other roof types and slopes, but are more costly to build. Simple gabled roofs are acceptable. Overhangs perform best when they’re between 1 1/2 – 2 feet in depth if enclosed or 8 inches if open.
2. Elevate the building.
Avoiding damage from flood waters is simple, build above them. Homes in flood zones are required to be built at or above the Base Flood Elevation (BFE) depending on where you’re building. For example, in Miami Beach, the first floor of a home has to at least be built at the same height as the BFE. In the City of Charleston, the minimum height is 1 foot above BFE, but in Charleston County, the first floor of a home is required to be built 2 feet above BFE.
The BFE is determined by Flood Insurance Rate Maps, or FIRMs, and is a regulatory requirement for floodproofing of structures. The relationship between the BFE and a structure’s elevation also determines your flood insurance premium.
3. Keep the rain out.
Rain comes from all directions during a storm, driving moisture into exterior walls. It’s therefore good practice to provide a drainage plane directly behind the siding to allow water to escape instead of getting trapped inside the wall.
Other areas susceptible to wind-driven water intrusion is attic vents, areas around windows and doors, soffits, wall penetrations for utilities, and cracks in exterior finish materials. Making sure these are properly detailed and constructed is critical to keeping your home dry.
4. Use materials that can get wet.
Two of the most common building materials widely used in hurricane and flood prone regions are also most susceptible to water damage. Can you guess what they are?
Well, the first is paper-faced gypsum board, also known as drywall.
The best thing to do is simply don’t use it. Using non-paper-faced gypsum on the inside of exterior walls is a better solution because it stands up to moisture better.
The second building material to avoid is fiberglass batt insulation. You know, the pink fluffy stuff.
Should that insulation get wet during a flooding or hurricane event, you’re gonna have problems. Instead, your home should be insulated with rigid foam or rock wool boards on the exterior. They’re hydrophobic, a fancy word meany that they tend to repel water.
5. Design the building so that it can dry out when it does get wet.
Once your home has been designed using the strategies above, the final step is to take a worst-case scenario approach, meaning you should consider what happens when things do get wet.
Walls, floors and ceilings should be designed so that they can be opened up and allowed to dry. This is easily achieved. For example, detailing walls so that they can be opened at the top and bottom allow for air flow to remove moisture in the wall.
In addition, consider thees recommendations for resilient design from the Urban Land Institute in their article Trying To Reason With Hurricane Season.