A barn can serve many functions, from a place to store farm equipment and feed out of the elements to a shelter for animals. If you look at the history of barns, it is easy to see that form follows function. A livestock barn follows a different style than a hay or multipurpose barn. One relatively easy type of barn to construct is a pole barn.
Construct a pole barn framing out of whatever materials you can find: wooden poles, rough-cut logs or even recycled telephone poles. Use tin, wood planking or even wood sheeting for the roof and sides. Tools required include a hammer and nails, posthole diggers and cement.
A pole barn takes its name from the framework on which the barn is constructed. In the past, this would have been poles made from tree trunks with the limbs hacked away. Today, the poles may be constructed any number of ways.
While some farmers still use rough-cut tree trunks for poles, others construct small "shed" barns using landscaping timbers or sleepers. Larger barns can be made by welding metal pipes together and then setting them in concrete. A barn can be constructed on a concrete foundation, or the poles can be set into holes dug into the ground, filled with concrete to hold them upright. The floor of the barn is left as dirt.
Construct the sides and roof with any material on hand. You can use sheets of tin or corrugated plastic for both the sides and the roof of a barn. Lifted these into place and hammer or weld them onto the pole frame.
By overlapping the tin and using roofing caps, you can make the barn more watertight. Often a pole barn will have one or more large sliding gates to allow heavy machinery to be driven inside, and a smaller door for human access when the gates are closed. If you require insulation, cover the interior of the barn in an inexpensive material such as closed cell foam. Unlike insulation approved for use in homes, this material provides the benefits of insulation while maintaining sanitary conditions in a dirty environment.