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.
A excellent horizontal storage shed can be a very useful space when used appropriately. However, since it's a space that is used for utility, homeowners often don't give much thought as to how it is arranged. During the spring and summer months, yard tools are frequently hulled in and out to assist in landscaping projects. In the winter, you may have to scramble to find snow shovels and sleds, certainly not something anyone wants to do in a harsh winter.