Tornado doors are sometimes referred to as safe room doors. First and foremost, a tornado door must protect against the flying debris and catastrophic increases in air pressure caused by a tornado’s extreme wind speeds, often in excess of 150 mph. A quality tornado door can be engineered and manufactured to withstand an EF 5 tornado with 250 mph wind speeds.
With climate change accelerating, an increasing number of communities are being impacted by extreme weather. Protective design is not just limited to the vehicle barriers and security entrances that prevent terrorist attacks, it also encompasses products that keep people and infrastructure safe from highly destructive natural disasters like tornadoes, earthquakes, floods and hurricanes. That’s why on Protogetic you will find a large selection of tornado doors from leading manufacturers. Whether a man-made violent attack or an extreme weather event, our mission is to help protect lives.
According to the National Oceanic and Atmospheric Administration (NOAA), tornadoes are the most destructive of all atmospheric storms. A tornado is a violently rotating column of air that extends earthward from a severe thunderstorm system. The tornado’s classic funnel cloud shape is only visible because of the circulating precipitation, dust and debris. Approximately 1,200 tornadoes hit the U.S. annually, killing an estimated 60 people (mostly caused by flying debris). The deadliest tornado year was 2011 when 553 people were killed. The single deadliest twister ever occurred in Joplin, Missouri when an EF5 tornado killed 158 people and caused 2.8 billion dollars in damages.
While hurricanes are designated by category (1-5) based on wind speed, tornadoes are measured by the Enhanced Fujita Scale. This metric, implemented in 2007, measures 28 damage indicators (building type, structures, trees, etc.) by assigning each indicator one of eight varying degrees of damage -- from minor visible damage to complete destruction. Based on this post-event damage assessment, the wind speed of a tornado is calculated. There are six (0-5) ratings for tornadoes.
Tornados are formed over land while hurricanes form in the warm waters of the ocean. In terms of protective design, tornadoes generally have much higher wind speeds and provide far less warning compared to a hurricane. A tornado’s lack of advance warning means it is nearly impossible to implement protective measures other than finding safe cover. The estimated warning time for a tornado now stands at just 13 minutes. Since a hurricane takes many days to sometimes a week to make landfall, there’s more than enough advance warning for storm preparation as well as evacuation. A formal hurricane warning is given 36 hours beforehand.
The severe wind speeds generated by tornadoes (200+ mph) are its most dangerous element that must be mitigated or neutralized by protective design and engineering. Fortunately, a tornado’s average duration of 2-15 minutes is far shorter than a hurricane’s lifespan that can thrash regions for hours to days with high winds, heavy rain and storm surge flooding. The path of destruction is also very different. While hurricanes can be 100’s of miles wide, the average tornado is about 300-400 yards wide, with the biggest ever recorded being 2.5 miles wide.
No. Many homeowners falsely believe that their residential steel doors will protect their home and families from a tornado’s destructive force. It cannot. Unless specifically designed, manufactured and tested under tornado conditions, residential steel doors are not capable of withstanding the extreme pressure, wind speeds and flying debris caused by a tornado.
Protection from flying debris is not only important to one’s physical safety but also protecting the building envelope. This is why one of the safety rules to survive a tornado is to never open any doors or windows. Similar to a hurricane’s high winds, a tornado can launch debris into doors and windows causing them to fail. Once penetrated, the rush of incoming air increases the pressure inside the building and can cause the roof to literally blow off. After this happens, it is entirely possible that the wind forces will flatten the entire structure. Only rated, certified tornado doors (and impact resistant windows) are capable of preventing debris penetration during these extreme conditions.
The International Code Council and National Storm Shelter Association’s ICC 500 test, also titled the Standard for the Design and Construction of Storm Shelters, is the gold standard for tornado protection. ICC 500 requirements were created from the data and recommendations from FEMA’s P-361 safe room criteria.
The ICC 500 test uses eight-foot long, 15-pound 2x4s, called a “missiles”, which are fired from an air cannon multiple times at more than 100 mph. The 2x4 missiles are directed at specific locations on the door – upper edge, lock and hinges. The criteria for hurricane impact resistant is a 9-pound 2x4 fired at approximately 33 mph. This gives you a clear indication of the difference between tornado versus hurricane wind speeds.
The most common manufacturing material for tornado doors is steel. However, some doors are made from aluminum or composites. Some steel doors are available with wood laminate surfaces for a more pleasing, “residential” appearance.
Yes. The glazing must be subjected to the same tornado test conditions. Impact resistant windows typically are made with several layers – a breakable outer layer and a laminate glass inner layer. The number of layers and their materials determine the window’s impact resistance. The goal is to absorb impact and prevent penetration, as this will compromise the building by allowing the air pressure to increase inside. Impact resistant glass additionally prevents shards of deadly glass from flying into living spaces. Of the estimated 60 deaths caused every year by tornadoes, most victims are killed by flying debris.
Protogetic carries certified tornado doors from top manufacturers. Find the exact tornado door your project requires by using our Protogetic filter to search multiple parameters instantly. Whether you are looking for high security doors, ballistic resistant windows or anti-ram crash arms, every Protogetic product page provides detailed documentation, including specifications, drawings and certifications. Everything you need to make the best decision, including a side-by-side comparison tool. Sign up for free now!
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