Particle board and plywood are composed of pieces of wood products that have been pressed and glued together. Although they are popular siding materials for storage units, they are not most people's first choice in regions where it rains a lot. For if water does work its way into these products (a possibility enhanced by their composite nature), then you're lost.
Will Your Outdoor Storage Building Be Big Enough? - Make sure the entry to the unit is wide enough to accommodate your largest piece of equipment, such as a gas snowblower, with room to spare. Many outdoor storage buildings that are at least 8 feet x 10 feet come with double doors, which usually eliminates this concern.