Post frame building construction isn’t necessarily a new form of construction. In actuality, it’s been in use for centuries, particularly along coastlines where shelters needed to be elevated above the water level.
It’s been around for a long time because it’s been known for ages that posts sunk into the ground provide excellent attachment points for wall joists, flooring and roof trusses.
Native Americans used this style of construction for lodges and other large buildings. Even Alexander the Great used post frame construction to build the bridges his armies used.
The biggest problem with post frame construction in the past has been the fact that organic wooden posts, sunk into the ground, decayed in time due to moisture absorption. This made the wood soft, weak and easy to penetrate.
Bacteria, worms, borers, carpenter ants and fungus could also cause wood rot, breaking down the wood fibers and creating instability in the posts. This caused major structural problems.
The only way to address the issue was to remove the decayed posts and replace them. This was very time consuming since everything attached to the pole had to be removed first; the post was then dug up, replaced, and everything was reattached.
Moving to Preservatives
The first type of preservative to help overcome decay was mud or swamp muck placed in the hole to cover the bottom of the pole. This created an anaerobic, or oxygen deprived environment.
This environment resisted the formation of wood eating bacteria and fungus while keeping worms and wood boring beetles away.
The Greeks took a major step to keep the moisture out of their post poles by coating them in olive oil to resist moisture and decay. The Romans were the first to coat their posts in tar, which resisted moisture and made the wood fibers inedible for microorganisms, carpenter ants, and termites.
The first modern type of wood preservative creosote, a wood tar derivative, was invented in 1832. Currently, we’re using chromated copper arsenate (CCA), the more environmentally responsible copper azole (CA), and the newest form of preservative micronized copper quaternary (MCQ).
These substances act as fungicides and insecticides, with a guaranteed below ground lifetime of 20 years or more. Longevity has come a long way for post-frame construction!
Modern Post Frame Construction
All modern post frame construction comes from the original concept of putting posts in the ground as supporting members, and using them as the frame on which the rest of the building is built.
The term “pole barn” is a direct reference to the post frame construction technique used to build barns, by sinking “poles” into the ground as the supporting structural members.
Although the basics remain the same, preservation of the wooden posts has always been the key to the longevity of these structures.
Modern wooden post-preservation includes plastic sleeves for the posts, footings that limit ground contact, pre-cast concrete columns, collars, and base plates. These adaptations assure a lifetime of preservation for below grade, sunken posts.
Modern procedures of post-preservation, combined with the fact that post frame construction has proven to be one of the sturdiest building construction methods, makes this type of structure one of the best building options with a versatility that is unmatched by virtually any other building technique.
Interested in touring a building to see first-hand the materials and workmanship? Contact us today and we’ll be happy to answer any questions you might have.