Building Back Better in Tornado Alley
Moore, OK, Mayor Glenn Lewis vowed yesterday, May 22, to pursue an ordinance to require reinforced shelters in every new Moore home. Many of the homes in the decimated town had neither above- nor below-ground shelters, leaving the residents to hide in interior rooms, bathtubs, and closets. While small interior rooms are certainly the safest place in an otherwise unprotected home, they do not guarantee safety.
Oklahoma, despite being a state regularly ravaged by tornadoes, has a very small number of homes (1 in every 10) with basements. Uncooperative soil conditions are the chief reason for this deficit, however a number of other causes come into play.
Oklahoma sits upon a diverse range of soils, from clay to loam and just about everything in between (PDF). Moore, specifically is based on a fine sandy loam, and basements built in the area are prone to water leaks, mold, fungus, and associated interior damage. The upkeep and associated costs of basements in this area are, in many cases, simply too much to bear. Additionally, dampness in the soil can cause a buildup in water pressure, putting a strain on (esp. underground) structures. A basement collapsing under severe water pressure would, in most cases, render the building above structurally unsound and uninhabitable.
Basements are common in areas that have a low frost depth. When you’re forced to build four to five feet below grade to bury pipes, adding a basement to the house has little to no associated cost.
In many Southern states, however, such as Oklahoma or Alabama (remember the 2011 Tuscaloosa tornado), the freezing depth can be as shallow as 18" below grade. Adding basements to homes in areas with this shallow a freezing depth can have massive associated costs, as there is no reason any prior sub-grade structure would be built. These, along with the costs of upkeep, make them an unpopular option places where basements would otherwise make sense.
However, this is not to say that basements are an entirely unavailable solution.
Recent “technological” advances (spray-on polymer line systems, basement drainage systems, etc.) can keep a clay-encased basement from getting too damp, and avoid mold, fungus, and structural damage. The soil condition at each site would have to be addressed, however, and would likely make the process of building a basement more expensive. The legends of basements being an Oklahoma homeowner’s critical weakness started in the 1940s and 50s and, while they still mostly ring true, contemporary construction methods make them less of an impossibility.
Another problem associated with the construction of basements falls in real estate. Basements are currently so rare a feature in Oklahoma that many listings do not list homes as having them at all. People searching for homes with basements are, in many cases, unable to find them, and wind up buying homes without. In terms of the housing market, basements are not necessarily an asset when selling a home, and are typically not financially worth the original homeowner’s while when trying to sell.
Shelters, Below and Above
Initial costs (this does not reflect any kind of upkeep) of home shelters range from $2,200 – $20,000, according to Mike Barnett a custom homebuilder in the Moore, OK area. A small concrete cellar built during new-house construction could cost as little as $2200, while a small basement could range between $15,000-20,000 and an above ground shelter could cost between $8,000-10,000. While expensive, Rachel Maddow points out in the 22 May, 2013 edition of her show that building a school classroom as a safe room would not be much more expensive than simply building a regular classroom.
Shelter from tornadoes is not limited to below ground structures. The National Storm Shelter Association tests above ground shelters (PDF), not only against high-speed winds, but also against blunt object impact. The leading cause of death in tornadoes is traumatic injury (21% percent of which is head injury). Above ground shelters are effective (and crucial) not only in that they don’t blow away, but that they can withstand the impact of flying objects (as would be the case in the event of a tornado).
Which leads us to what may be the most viable solution to the resilient rebuilding dilemma – Moore, OK had no available community shelter, either above or below ground. Even the most damaged schools, while equipped with a disaster plan, did not, in fact, have a shelter.
While personal shelters are, for many people prohibitively expensive, a community shelter would take some of the financial burden of the shelter off the residents, as well as providing a place of refuge for a larger range of people. These could be put in place at schools, mobile home parks, areas with heavy pedestrian traffic, commercial centers, apartment complexes, etc. to provide shelter for as many people as possible.
Incentives & Awareness
The National Storm Shelter Association suggests that implementing government incentive programs that encourage the construction of shelters, both above and below ground, would encourage residents to build when they may not have before. By eliminating some, if not all, of the financial burden, it is likely that people will be able to consider the long term safety benefits as well as the short term financial implications.
It seems that effective solutions would also include an education component on advances in disaster-resistant construction techniques, private and communal shelter alternatives, price points and the availability of government support for their installation.
Community shelters are a plausible option in areas where people cannot afford their own, and may even be preferable. (It may be more feasible for community projects to receive state and/or federal funding.)
The notion of a tornado-proof home does suggest advancements in tornado aware construction, and is (hopefully) not entirely without merit.
National Storm Shelter Association:
Texas Tech University Wind Science and Engineering Research Center:
Storm Prediction Center:
Oklahoma Geological Survey: http://www.ogs.ou.edu/pubsscanned/EP9p16_19soil_veg_cl.pdf
National Public Radio: