The problem with timber posts now compared to 50 years ago is that there were only so many old gums about. The trees that are currently getting cut for posts are younger and will not last as long. Not only that — Suitable trees are getting scarcer and prices are rising, so it’s in everybody’s best interest to make them last as long as possible.
The mixed gum posts we get are nominally Class 1 or Class 2 in the ground and cypress is also class 2. Class 1 means a post life of 15-20 years and Class 2 is 10-15 years. But timber as a natural product will have a lot of variation so even the same species in Class 1 can actually be from 10 years to 30 years.
You can add 5 years to the life of your post by applying a bitumen membrane to the in-ground portion of your post plus 100mm of the above ground section. It’s a low cost, low effort solution and available ex stock when you order your posts. Simply follow the instructions on the tub for longer lasting posts!