Building Hurricane Proof Structures & Tornado Proof Homes in Georgia with Concrete & ICF Construction
A photo showing an ICF home under construction that took a direct hit and is still standing while homes to the left and right using traditional construction were destroyed
It seems that almost every day we wake-up to newscasts of the aftermath of some form of natural disaster – tornadoes, hurricanes, floods, earthquakes, and wildfires. Invariably, the widespread devastation that we witness in the wake of these natural disasters immediately tells us that as a nation, we are not building our homes, schools, and businesses strong enough to resist these incredible forces delivered by nature. Even in areas of our country that experience 25 or more tornadoes each year, new building owners are not demanding disaster-resistant construction; furthermore, most of the building owners who experience the total destruction of their homes or facilities due to one of these natural disasters decide to re-build using the same traditional building methods, primarily wood-frame, that demonstrably failed to protect them from the catastrophic effects of these super storms & seismic events.
So, how do we protect building occupants and our homes and facilities from the devastation that is wrought by these extreme forces of nature? Answer: Use time-proven disaster-resistant construction methods to build future homes, businesses, and public and local governmental facilities such as schools, universities, fire and police stations, and more. Disaster-resistant construction requires that we build a Disaster Resistant Shell (DRS) as coined by C.E. “Joe” Warnes, a structural engineer specializing in disaster-resistant concrete dwellings. As the lead presenter of an engineering seminar at the 2014 National Hurricane Conference entitled “Super Hurricanes and Tornadic Wind Velocities: Structural and Architectural Design and Construction Details for Single Family Houses”, Warnes identified the major causes of natural disasters in the U.S. – tornadoes, hurricanes, earthquakes, and wildfires – and further highlighted the first two as the most common and most destructive: EF 3, 4, and 5 tornadoes and Category 4 and 5 hurricanes.
According to Warnes, the most proven DRS is an all-concrete structural shell that ties the roof, floor(s), and walls together into a monolithic structure using steel reinforcement. Though other systems may provide tornado resistance, the reinforced concrete structural shell – when built with ICFs - is the only DRS that has the capability to stand-up to 250+ mph tornado force winds while also providing its owners with superior energy savings (from 30 to 70% + reduction in cooling and heating costs); a 4-hour fire rating; resistance to termites, rodents, mold, and mildew; excellent sound absorption ratings (about one-quarter to one-eighth sound penetrates an ICF wall when compared to wood frame walls), and remarkably low air infiltration.
EF3 Tornado destroys a well-built home using wood-frame construction. Only interior rooms remain. Courtesy Wikipedia.
Before describing further the time-proven capability of reinforced concrete structures to withstand nature’s most intense wind forces and seismic events, it is important to underscore the extremely limited abilities of wood frame homes – even those that some “housing construction experts” claim to be tornado-proof – to stand-up to anything greater than an EF2 tornado. According to Warnes and Kenneth Luttrell, a licensed structural engineer who has chaired building code communities seeking to improve buildings’ wind and seismic resistance, in their jointly authored article: ‘Tornado-Resistant Concrete Houses’, “both EF4 and EF5 tornadoes leave wood-framed houses as piles of rubble. A tornado as small as an EF3 usually renders a conventional wood-framed house unsalvageable (see Wikipedia photo for this category). Even an EF2 will do costly damage, perhaps making retrofitting of the house impractical.” They also stated: “The lessons learned – particularly at Tuscaloosa, Alabama; Joplin, Missouri; Moore, Oklahoma; and Illinois – are clearly delineated by the fact that not one single wood-framed house has survived in the direct path of EF4 and EF5 tornadoes. They have all indiscriminately been turned into kindling.” (To obtain more information on this topic or to read this article in its entirety, please go to www.tornadoproofhouses.com.)
This all concrete DRS house in Guam is of the type of home that had begun being built on this island 50 years ago to withstand the enormous wind speeds of typhoons. Some of the earliest DRS homes that were built on Guam have been subjected to six typhoons the majority of which were rated as Category 5 (on the Saffir-Simpson scale used to measure hurricane wind speeds in our country and other countries in the Atlantic basin) and higher, and an 8.1 Richter Scale earthquake without sustaining any measurable damage.
The performance of the reinforced concrete Disaster Resistant Shell in the real world laboratory attests to the superior resilience of these structures. More than half a century ago, the U.S. began building disaster-resistant structures using steel reinforced, all-concrete (roof, floor, and walls) houses on the island of Guam after Typhoon Karen (September 1962) and Typhoon Olive (April 1963) cleaned the island of most of the conventionally built homes. Typhoon Karen, the Pacific Basin equivalent of an Atlantic Basin hurricane, recorded wind gusts up to 207 mph. In response to a request for assistance from the Guam governor, President Kennedy ordered the development and construction of replacement houses that would be typhoon resistant.
Since the beginning of this project in 1963, thousands of reinforced concrete houses have been built on this island; and, though it has been subjected to the wrath of six additional typhoons (the largest of which was Typhoon Paka in 1997 with gusts reaching 240 mph), many of which exceeded the wind speeds for the most severe Atlantic hurricanes experienced in the U.S., none of these homes have sustained any wind damage. In a 2006 E-mail to Warnes from Alfred A. Yee, the structural engineer who designed these homes (referred to as Dededo houses after the most populated village in Guam), Yee stated: “The Dededo houses have been in existence for 40-plus years, and they have gone through many typhoons that make Katrina look like only a rainstorm. There were typhoons where winds were recorded at 234 mph when the anemometer broke. Whatever they were, no one knows!” (See videos below.)
In addition to tornadoes and hurricanes (typhoons), reinforced concrete shell buildings have demonstrated their resistance to other terrifying forces of nature to include earthquakes, wildfires and floods.
Earthquakes: Also known as a region for intense seismic activity, Guam experienced earthquakes in 1993 and again in 2005 with recorded Richter scales of 8.1 and 6.3, respectively that failed to cause measurable damage to the reinforced concrete houses that have been constructed there since 1963.
Following a 2007 wildfire that ravaged this neighborhood San Bernardino, Ca., the only homes still standing (virtually unscathed) were built with ICFs; the wood-framed homes were reduced to ashes.
Wildfires: A raging wildfire roared through the San Diego suburbs in the fall of 2007, forcing over half a million people from their homes and destroying over 2000 houses. In one particular subdivision in San Bernardino, all of the traditionally-built homes were charred ruins down to the foundations and the only structures that remained standing (virtually unscathed) were three ICF homes.
Points to be remembered in relation to the Fire Resistance of Concrete:
- In fire, the components of concrete (cement and aggregate) are chemically inert and so virtually non-combustible.
- Additionally, concrete has a slow rate of heat transfer and intrinsically act as a fire shield.
- Concrete walls are generally rated with a 4-hour fire rating
In addition, the EPS foam used in ICF forms will not burn – it will melt when exposed to high temperature fires, but it will not contribute any fuel to the fire. In fact, due to the addition of a flame retardant added to the EPS foam, it is self-extinguishing.
During Hurricane Katrina in 2005, a Gulf Coast concrete house stood firm against a 20-foot storm surge; however, all of the other homes in this neighborhood were swept down to their foundations
Floods/Storm Surges: In recent years, ICF homes have proven their ability to withstand disasters in the face of massive floods and storm surges associated with large hurricanes in the U.S. A beachfront ICF home in New Jersey withstood Superstorm Sandy in 2012, even after having its siding scrubbed off by the pounding waves. During Hurricane Katrina in 2005, a Gulf Coast ICF house stood firm against a 20-foot storm surge; however, all of the other homes in this neighborhood were swept down to their foundations.
Concerning the resistance of ICF homes to floods in general, Warnes in his article entitled ‘Disaster-Resistant Shell Houses’, states that “flood waters are unlikely to deform or float a properly designed and constructed all-concrete “box,” and the salvage value of a concrete structural shell system would be far superior to that of a wood-framed house.
After Hurricane Sandy, the ICF home on the left was structurally intact, with only a section of exterior siding missing while the house on the right, just 3 lots down, was virtually destroyed.
See the complete article showcasing ICF & Disaster Resistant Construction on the Concrete Network.
Percussive (blast) loads: Though not a product of nature, percussive loads due to the discharge of explosives can have a devastating effect on buildings. The U.S. military has been so impressed with the disaster-resistance of ICF structures that it conducted blast resistance tests using 50-lb charges of TNT. In view of the impressive results of these tests, the armed forces are frequently specifying ICF construction for “force protection” requirements.
FORTIFIED BUILDING - The Insurance Industry Takes Note:
A few years ago in the wake of some of the largest natural disasters that have ever stricken the U.S., the insurance industry was reeling from the enormous payouts to fund the recovery of whole communities that had been devastated by these massive forces of nature. In response, the insurance industry under the auspices of the Insurance Institute for Business & Home Safety (IIBHS or IBHS) – an organization whose mission is ‘to conduct objective research to identify and promote effective actions that strengthen homes, businesses, and communities against natural disasters and other causes of loss” - created the Fortified Building program for the purpose of encouraging building owners to build more durably. (See www.disastersafety.org for a more detailed description of the Fortified Building program.)
The Fortified for Safer Living program, one of the two Fortified programs that specifically address new construction, explicitly encourages the use of ICFs. In the same “ICF 101” article that appeared in the July/August ICF Builder Magazine, Chuck Vance, IBHS’ “Fortified” program administrator, says, “We’re impressed with the superior wind-load capacity of an ICF wall. It also has other benefits as well, including resistance to fire and fewer problems with water damage.” The Fortified for Safer living program’s standards are designed to increase a new home’s resistance to whatever natural hazards threaten the area where the house is located. The IBHS describes the Fortified for Safer Business as a code-plus new construction program that offers a package of improvements that greatly increase a new commercial building’s durability and resilience to both natural and man-made hazards. This program is aimed at small to mid-size businesses that require protection from high winds, floods, hurricanes, wildfires, earthquakes, freezing weather, hail, and water intrusion.
The owner of this 4800 sq.-ft. house on the Florida coast earned an annual savings of $18,000 on this homeowner’s insurance policy after his home qualified for Fortified credits gained from its ICF Disaster-Resistant Shell.”
Benefits for Home Owners of Fortified for Safer Living (FFSL) homes:
See the detailed Fact Sheet on the Fortified for Safer Living program.
Benefits for Owners/Managers of Fortified for Safer Business (FFSB) Facilities:
- Greatly reduce the potential for property damage from natural disasters and interior fire;
- Maintain or increase a steady revenue stream and strengthen community ties by providing critical goods and services in difficult circumstances;
- Lower the overall cost of the community’s recovery following a natural or man-made disaster;
- Maintain or increase market share during and after a widespread catastrophe;
- Retain employees and reduce employee stress;
- Improve competitive advantage by providing continuous services to the community
See here for a complete listing of all of the benefits for owners/managers of FFSB facilities or other more detailed information about the FFSB designation, access the ‘FORTIFIED for Safer Business™ Fact Sheet’.
THE ICF BUILDING SYSTEM – The single-best solution for Disaster-Resistant Construction
The evidence clearly demonstrates that buildings constructed with reinforced concrete – floors, roof, and walls – constitute the only Disaster-Resistant Shells that have withstood everything that nature can unleash against man-made structures over the past 50 years. As more prospective building owners are discovering the superior resilience of reinforced concrete construction, they are also rapidly learning that ICFs are the single-best concrete building system for yielding the best return on investment (ROI) and the lowest total cost of ownership (TCO). As a bonus for choosing the ICF building system, you receive:
- Unparalleled energy efficiency due to the high R value of continuous EPS insulation, ultra-low air infiltration, and the thermal mass of concrete
- Faster construction times than concrete block and wood-frame
- Remarkable sound absorption ratings - in excess of an STC of 50 (only about one-quarter to one-eighth as much sound penetrates an ICF when compared to wood frame)
- Design options and flexibility: architectural details such as arched doorways & windows and radius walls are much easier to build compared to wood-frame or block construction; longer clear spans are permitted because the walls can carry the loads and steel beams required by these designs; accommodates construction in winter time in northern climates; permits the use of any type of exterior finish
- Construction costs: the cost of building is on a par with wood-frame construction – the average ICF home is 3% to 5% higher than wood-frame, but the homeowner receives a payback immediately in the form of energy savings and insurance premiums (depending upon the insurer and the specific location)
No longer are the owners of new concrete homes burdened with the stigma of institutional-looking structures that don’t provide appreciable insulation and are resistant to making decorative changes in the interiors. As stated by Joseph Warnes during his presentation at the 2014 National Hurricane Conference, “For the first time, we today have a solution to the age-old challenge of building attractive, energy-conservative houses that are comfortable and at the same time secure from destruction by the severest forces of nature.”
Finally, the growing success of ICFs is being fueled in this country in part by the U.S. tradition of building wood-framed housing using prescriptive design rules. In effect, this tradition has created a homebuilding industry that is dominated by carpenters. Since ICF structures are readily erected by using common carpentry methods, and that the finish materials for ICF walls are virtually the same as those used in traditional wood-frame construction, carpenters can readily migrate to ICFs when their customers request this type of construction.
Effects of Typhoon in Guam on a non Disaster Resistant Home
In December 1997, Typhoon Paka pummeled the island of Guam for 6 hours with wind speeds measured up to 236mph before the monitoring equipment was destroyed. Notice that the roof is the first component of the Owen family’s non-DRS home to be swept away & destroyed; once the roof is gone, the remaining structure of the home is fully exposed to the fury of this typhoon. Fortunately, this family was able to find shelter in a concrete church nearby.
Effects of Typhoon in Guam on a Disaster Resistant Constructed Home
In contrast to the Owen family that was living in a traditionally built home, the occupants of this DRS home (reinforced concrete walls, roof & floors tied together into a monolithic structure) are protected from the 150mph winds produced by Typhoon Pongsona. Note the terror experienced by the family in the previous video in their traditionally-built home versus the confidence & calmness shown by the family inside this DRS concrete house.