Safe rooms or storm shelters can be any size as long as you build them to the requirements outlined in the FEMA brochure. This storm cellar chamber is 7×8 feet, but it could easily be 4×4 feet.
Consider the available area, the number of persons you anticipate protecting, the additional role the room will serve, and your budget when determining the size.
The walls and roof of the storm shelter have a sandwich skin with two layers of 3/4-inch plywood with opposing grain directions. Plywood absorbs most of the shock from flying items, while a layer of 14-gauge steel on the room’s “safe side” inside further shields debris.
You can install the skin inside or outside the studs as long as the steel sheeting faces within the storm shelter chamber.
Additionally, install the sandwiched skin on the studs’ exterior surface wherever possible. Construction will be more straightforward because you won’t have to cut through steel to run wiring or install electrical boxes.
You’ll also be able to attach a decorative layer of drywall to the plywood. This part should be on the exterior and the studs on the inside.
Because those locations were unreachable from the outside, we had to put the sandwich on the interior surfaces of the two walls facing the concrete block and on the ceiling. To secure the drywall screws, we bonded 12 furring strips to the interior-mounted steel on the ceiling.
Only humans and dogs, not door-busting debris, may enter a storm shelter with a steel door set in a steel frame with three deadbolts opposite heavy-duty hinges.
You can build a sheathing made of steel and plywood with either 3-inch self-tapping screws (on Amazon) or 3-inch deck screws (on Amazon) 6-inch apart. With 10d nails (on Amazon) placed every 6 inches, you”’ fasten all doubled framework members to each other on each side.
Lastly, excluding the 14-gauge steel sheets, full-service lumberyards either have or can special-order all components. You’ll need to create this storm shelter underground room.
Only have one comment about the video— putting the shelter in a garage floor could be dangerous if the vehicles get moved onto the trapdoor either by the tornado or debris.