The quickest and easiest way to tell if your concrete slab foundation is thick enough for a Tornado Alley Armor above ground storm shelter….. Drill a small hole through your concrete slab using a hammer drill and masonry bit. If you’re a minimum of 3.5”- 4” in before the bit punches through you’re just fine. If your home was built within the last 40-50 years, and if it was build in a city with building inspectors for new construction, chances are great that your concrete is adequate for an above ground safe room.
If the reinforced concrete slab is found to be inadequate, we’d have to regroup and try to find an alternate location for your storm shelter, or make arrangements to beef up the existing location. There are a couple of options to modify the existing location which we’d have to discuss, and those options would probably add $1200-$1500 to the total cost of the tornado shelter. FYI- in all our installations we’ve only come across one that didn’t qualify.
Some info on the steel requirement for above ground safe rooms: It is recommended to add protection for the absolute worst case scenario. The idea is that if the concrete were put under enough stress that it actually flexed and failed, the steel embedded in the concrete should keep the broken part of the slab and the safe room attached to it connected to the main mass of the slab long enough for the tornado to pass. To our knowledge this scenario has never been observed. Also, if there are any structural considerations to the garage, such as being partially under grade like you’d find on a split level house, which would significantly reduce the loads on, and improve the performance of the slab.
There’s a way you can check the concrete in your slab foundation yourself if you like. If you purchase one of the sensors we use, around $115 from Walmart.com, and you buy a safe room from us, we’ll buy the device from you for what you paid for it when we install your safe room….assuming it’s in working order. If there’s no steel and you don’t purchase a safe room from us, we’ll still buy it from you for $60 if you want to get rid of it. It’s very simple to operate.
Feel free to call if you want to discuss or order. www.tornadoalleyarmor.com or toll free 918-518-1551.
Thanks,
Leslie McGee
CEO