Before the 1980s, meteorologists would tell people to open their windows if a tornado was approaching. The belief was that this would keep your house from exploding.
Science has since proved this to be a myth and a waste of valuable time that you should be using to seek shelter. You don’t want to be anywhere near a window when a tornado hits.
Tornadoes Don’t Destroy Homes Because of Suction
Tornadoes form from a spinning upflow of air into a thunderstorm. This upflow creates a drop in air pressure, but not enough to damage a house. Although this pressure difference has never been measured, it is thought to be less than 1.5 lb./square inch.
Normal atmospheric pressure is 14.7 lb./square inch at sea level. Although a sudden 10 percent drop in air pressure might blow out a large window, it’s nowhere near enough to make a house explode.
We have all seen pictures of a tornado’s aftermath — a sea of shattered rubble and debris where a happy neighborhood stood only hours before. If those houses didn’t explode then what the heck happened to them?
The Real Culprit is Wind
Wind speeds in a tornado can be up to 300 miles per hour. Even small EF1 tornadoes have winds in excess of 100 miles per hour. Wood-framed houses are simply not designed to withstand these storm-force winds.
100 mph winds can tear off shingles and siding. Windborne debris will break out windows and can penetrate walls. Once windows are broken, the wind pressurizes the house, increasing stress on walls and the roof.
Strong wind blowing over the roof creates lift due to the Bernoulli Principle, just like an airplane’s wing. If the roof isn’t built to withstand high winds, the wind can pull off sheathing or lift the roof from the house, trusses and all.
Studies using wind-tunnels and engineering models have finally shown why houses seem to explode when hit by a tornado.
First, the wall facing the storm-force winds collapses inward. Then, the roof is torn away and the remaining walls collapse outward. Finally, the winds pick up and scatter anything loose, like personal effects and building materials.
Where is the Best Place to take Shelter?
In a small tornado, you may be able to take shelter in an interior room or closet. The general rule is to put as many walls as possible between you and the storm. However, there is NO safe place to shelter in a house that’s being torn apart by a tornado.
The only safe place to shelter from a tornado is in a storm shelter designed to withstand not only extreme storm-force winds, but also impacts from windborne debris.
Your shelter should be easy to access quickly in an emergency, perhaps in a basement or a garage. You may have very little time to round up the family and get to shelter. Additionally, the weather that often precedes tornados may make it challenging to get to a shelter if it’s located outside and away from your house. Our modular saferooms are easy to install inside an existing structure.
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