Simply put, a Pole Building is a structure that is built around large pressure treated timbers sunk directly into the ground, and roof trusses attached to an upper perimeter frame. Horizontal framing spanning the main timbers typically of 2 x 4 dimension lumber provides additional stability, as well a a surface to nail siding or roofing to. Pole buildings can be built quickly and inexpensively, compared to conventional framed structures, but do not do well in areas of unstable soil, deep frost lines, or areas that have problems with termite infestation.
Timber framed buildings have been around for thousands of years, but the framing timbers needed to be kept above grade, or else they would soon rot or be riddled by termites. This has usually been accomplished by building the structure on a concrete or masonry slab or footer wall or pier, which is a major cost component of a building. Pressure treating wood with a preservative such as creosote or CCA provides at least several decades of resistance to rot, allowing the timber to be set on stable soil below the frost line. Once the building is framed, wood or steel siding and roofing is applied to horizontal stringers which span the framing timbers, and doors and windows are added to suit the particular needs of the user. Because of the relatively low cost and ease of construction, they have become popular in many rural areas as a replacement for regular timber framed barns, shop buildings, garages, pavillions and the like. Because the timbers eventually will rot, they are not well suited where something really permanant is desired, but with minimal care and sound construction techniques, they can provide several decades of useful service before needing replacement or repair. They also are not particularly easy to insulate or finish off into office space or living quarters, at least by American standards, so their main application continues to be primarily as utility buildings.