Interior Above Ground Hurricane - Tornado Shelter Notes

If you are in the planning stages of building a new home, you can incorporate a safe place to hide from tornadoes and hurricanes if you are willing to part with about 40 square feet of floor space and about $2,500. If you are the slightest bit handy, you can get the cost down to less than $700.00.

It Doesn't Need to be Big!

Dreadful windstorms can blow against your house for as little as 20 seconds (a fast moving tornado) or they can last for hours (a creeping hurricane). In either case, a family of 5 people can huddle in a 4 foot by 8 foot shelter for this time period with an acceptable degree of comfort. If you feel you need more room, then plan for it now.

Solid Walls and Ceiling

Tornadoes and hurricanes lift debris into the air and transport it at great speeds. A seemingly harmless 2x4 can become a missile. Cars, brick, concrete block can all be easily lifted into the air and carried for significant distances. To protect against impact of heavy objects like this, your shelter needs to be solid. Hollow concrete block simply won't do. What's more, the block walls need to be steel reinforced. An 8 inch concrete block structure that has steel bars in the cores at 16 inches on center and has all of the cores filled with a pea gravel mix of concrete is incredibly strong. Top this off with a 4 inch thick poured concrete roof that is also steel reinforced and you have a great place to hide from storms.

Pin Things Together

You need to secure the concrete block walls to the concrete floor/slab and the roof of the shelter needs to be tied to the walls. You do this by inserting steel rods in the wet concrete. The rods in the floor slab need to extend up about 2 feet and be placed so they hit the centers of the block cores. This takes some precise layout work. The steel for the roof needs to be placed into the wet pea gravel concrete that fills the top courses of the concrete block walls.

A Sliding Door

The door to the shelter needs to slide. A hinged door can be sucked off its hinges. The best door would be one that has a solid barn door track and fits into a pocket built into the block. It needs to have a restraining bracket at the bottom corners of the door as well. This keeps the door from blowing in or out due to extreme wind pressures. The door can be made from two sheets of 3/4 inch plywood screwed together and covered with minimum 14 gauge metal sheeting. It doesn't have to look pretty. This door and how it stays in place during the storm is critical. If you can't figure it out, then ask an experienced carpenter to assist you with this job.

The Roof

The inside height of the entire structure needs to only be 7 +/- feet tall. This allows the overall height to easily fit under roof trusses that are placed on standard height walls. This is the hardest part of the job as you will need to lift about 15 five gallon buckets of concrete up onto the temporary form that supports the roof!

For information on a special underground tornado - storm shelter, visit and read this column.