Sapwood is the usually paler band of ‘living’ wood that is just under the bark of a tree. It carries water and nutrients up and down the tree and in all species has a lower durability when exposed to weather. Sapwood positioned horizontally to rain might last 3-7 years, depending on a range of factors. Good builders would position any sapwood away from this exposure.
The other inner wood is known as the heart or the heartwood and in some species, such as Golden Cypress, this wood has a natural durability. And because the trees we harvest at Golden Cypress are senescent, slow-growing, very old trees, the proportion of sapwood present is generally very low. Here’s a picture of the end-grains of a pack of our sleepers – note how little sapwood is present.
On the other hand, here’s a picture of some cypress pine posts being sold at a large hardware retailer. Cypress pine trees have been relentlessly overharvested in NSW and QLD and little remains other than very small diameter fast growing specimens. Notice the prevalence of sapwood.
* For in-ground use we recommend applying Termseal Creofen-10