The following is compression test to determine the driving strength of our composite posts. The average is 78,592 psi. For many common species used in 4x4 posts (such as Douglas fir or Southern pine), the compressive strength parallel to the grain is typically in the range of about 7,000 to 8,000 psi. This aligns well with the claim that our composite—at 78,592 psi—is roughly 10 times stronger in compression than a typical wooden post.

The following is a fexural test to determine the flexibility strength of our composite posts. 

An average wooden 4x4 post typically has a flexural (bending) strength in the range of about 7,000 to 9,000 psi. For estimation purposes, let’s use an average value of around 8,000 psi.

Calculations:

• Wooden post flexural strength: ~8,000 psi

• Our post flexural strength: 5,300 psi

This means the wooden post can withstand about 8,000 psi before breaking, compared to our post at 5,300 psi. In other words, the wooden post is roughly:

8,000 psi ÷ 5,300 psi ≈ 1.5

This implies that under similar conditions, our posts would deflect more—that is, they are about 1.5 times more flexible than a typical wooden post.

Data for degradation of plastic types are widely available.  Given the mix of plastics in our composite posts, we can conclude an average life expectancy of 300+ years, which is easily 20x longer than that of a modern wooden post. Our posts are stronger than older composite posts because we aim to use all types of plastic in our forumulation, as well as a UV stabilizer.