WHEN FENCEPOST ROT SETS IN
The most commonly used trees for fenceposts are softwoods – pine, larch and spruce. They are fast to crop and easy to work with. They may grow quickly, but they tend to rot equally as quickly, even if ‘pressure treated’ where preserving chemicals are applied or injected. A fairly loose and open cellulose structure of this sort means water can quite easily gets into the post. When frost comes the water in the post expands and starts to weaken its integrity.
In summer, in hot spells, the wood in the post contracts, further compromising the structure through cracking. Essentially your ‘dead wood’ is subject to the erosion process of ‘freeze-thaw’ that has the power to split granite boulders! Furthermore, all these cracks and crevices that open up attract micro-organisms that happily feast on the cracking wood and lead to further deterioration and decay. In warmer parts of Britain this happens all the more quickly.