Storm shelter

Average storm shelter

An average storm cellar for a single family is built close enough to the home to allow instant access in an emergency, but not so close that the house could tumble on the door during a storm, trapping the occupants inside. This is also the reason the main door on most storm cellars is mounted at an angle rather than perpendicular with the ground. An angled door allows for debris to blow up and over the door, or sand to slide off, without blocking it, and the angle also reduces the force necessary to open the door if rubble has piled up on top. The floor area is generally around eight by twelve feet (2.4 by 3.7 m), with an arched roof like that of a Quonset hut, but entirely underground. In most cases the entire structure is built of blocks faced with cement and rebar through the bricks for protection from the storm. Doing so makes it nearly impossible for the bricks to collapse. New ones are sometimes made of septic tanks that have been modified with a steel door and vents. Some new shelters are rotationally molded from polyethylene.