How do I Hurricane-Proof my house?

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How do I “Hurricane Proof” my house?

Harper's Ferry Flood Sign 2.jpgHarper's Ferry, WV: Notice vertical sign (brown) showing historic flood levels.
The bad news is that it's impossible to completely hurricane-proof your house even if you're hundreds of miles in-land. One of the most damaging aspects of hurricanes and tropical storms is the rising water from the storm surge if you're near the beach or flood waters from creeks and rivers inland. To see what I mean, go to Harper's Ferry, West Virginia, make sure you look for the building with the markers up the wall that shows the flood levels in the middle of town from the different hurricanes (see picture).   Of course, you could be smart, and buy the perfect house with the right sheltering hillsides on high ground, but we typically buy our houses on beautiful sunny days and only think of hurricanes months or years later when we hear one may be on its way. Then, time gets short and we wonder what we can do.

For rising water, there is one thing you can do to prepare that could save you a lot of money, and that's to be ready to quickly build a temporary water barrier, and the most common temporary barrier is a sandbag wall or dike. 

Sandbag walls can be small and simply act as a water barrier in low-lying doorways or windows. These applications of sandbags have saved people thousands of dollars. There are many stories of next-door neighbors, one with a basement full of water and one that's relatively dry and the difference was a sandbag barrier in doorways and window-wells. If you click HERE, you'll see a YouTube video from the U.K. showing people in a town how to effectively fill and pile sandbags in their front doorway. Sandbag walls are usually one bag thick and stacked in a staggered pattern. SandbagDoor.png 

Sandbag Dikes are a little more involved, but still doable with some preparation. These dike walls have to stand more water pressure and are tapered up from a broader base and stacked in a staggered pattern. Dr. Kenneth Hellevang is a professor of engineering at North Dakota State University and he published a terrific paper on how to build a sandbag dike. vCalc has taken his paper and the math that it contains and created a useful calculator (Sandbag Wall Calc) to help compute the materials needed for building sandbag walls and dikes. When you enter your numbers, vCalc's Sandbag Wall Calc will tell you:

  1. How many sandbags you'll need to build a dike based on the height and length of the barrier you need to create.
  2. How much sand you'll need for the dike to fill the bags.
  3. How many sandbags needed in a simple wall or window-well.
  4. How much sand you'll need for a simple wall or window-well.
  5. How long it should take you to fill any number of sandbags based on the number of people working.
  6. The weight of the sandbags

The link to the free calculator and it's info is here: https://www.vcalc.com/wiki/Sandbag+Wall+Calc

The engineering science that you'll see on the calculator page is from Dr. Hellevang's paper, and it includes step by step instructions and is definitely worth the ten minutes to read.

Where do you buy sandbags and sand?

Buying sand is pretty straight forward. You can sand buy in bags from your local home improvement store, but this is only economically feasible if you're building small barriers for doorways or window-wells. If you're thinking of a longer wall or dike, sand by the bag will cost too much. For the bigger applications, buy sand in bulk. You'll have to check the Yellow Pages or the web to find a quarry and have them deliver the sand to you by the truckload. $200 for five tons delivered isn't bad, and that's a lot of sand (~3.15 m3).  Sand is an important part of the construction industry for making concrete, so you probably have a place that sells it in bulk in your county. In either case, use the calculator to compute how much sand you need.

Buying sandbags is different, but the good news is that most of the DIY home improvement stores sell sandbags, but they typically have to order them. So you'll want to compute how many you think you need and have them ordered in advance. They obviously come un-filled with sand, are pretty light and don't take up much room in storage. But you'll really be glad you have them when the time comes to save your home from rising water. A quick list of places to buy sandbags on the web follows: