To figure our storage requirements, we sat down together for a few hours and created a detailed list of the groceries and supplies we typically bought and the quantities we used on a weekly or monthly basis. Once we had determined the quantities of items and the rough sizes of the containers they were packaged in, I bought enough half-inch thick exterior plywood and nails to build a stockpile cabinet that could hold 3 months worth of the items on our list. It was cheap, less than $40, quick to build, and ended up providing more than enough space. We’ve used that cabinet ever since.