A door failure can lead to serious injury or death during a catastrophe. Choose a door assembly that includes locks, hinges, frame, and attachment devices that have been tested to withstand the wind, pressure, and impact of serious storms like tornadoes and hurricanes.  Storm shelter doors are heavy and expensive, but common steel doors that are often used in residential and commercial construction can’t withstand the impact of tornadoes and hurricanes. You may be able to find storm-rated doors at home improvement or hardware stores, but you may need to go online to order a specialized storm room door. Use the measurements of the door you plan to install so you can create an opening that will fit the frame. Measure your door with a ruler or tape measure, then measure the height and width on the studs of the open wall. Use a pencil or marker to mark where you need to cut away the studs. Make sure the door frame is at least 7 feet (2.1 m) tall so you can fit through it. Cut evenly along the lines that you marked on the studs to fit your door frame. Remove just enough of the studs to accommodate your door frame. You can lightly sand the cut edges of the studs with 180-grit sandpaper if they’re jagged or uneven. Position the frame in the opening and then nail it into place with casing nails. Then, install the door by attaching the hinges to the frames as directed by the manufacturer’s directions. Make sure the door is level and the hinges are secure in the frame. Install any additional specialized attachment pieces that are directed.  Use any screws or nails that are included in the door assembly. Open and close the door to make sure it’s working properly. Use a level to make sure the frame of the door is even. Once the door is installed, place steel sheets over the open studs and secure them by driving #10X2-inch (#10X5.2 cm) screws into each of the corners. Then, cover the sheets with plywood and drive #10X2-inch (#10X5.2 cm) screws through them into the wooden studs to secure them. Install an additional layer of plywood to complete the wall.

Summary:
Use a door assembly rated to withstand tornadoes. Measure and mark the size of the door frame on the open stud wall. Cut away the studs with a circular saw to fit the door frame. Install the door in the opening according to the manufacturer’s directions. Cover the open wall with steel sheets and 2 layers of plywood.