Timber rot occurs when timber is allowed to become damp and remain that way for a long period.
THE PROBLEM: Timber rot is common where timber meets the ground – for example, in timber stumps (as noted earlier), decking, pergolas and fencing. Timber rot will erode the structure of timbers and is encouraged by damp conditions under the house and around timber in contact with the ground.
WHAT TO LOOK FOR: Timber rot is slow to move, but nonetheless damaging. Signs of timber rot include soft or spongy timber. If you poke a screwdriver or similar into the timber, it comes away in shreds or pieces. This will be particularly common underground, so you might have to dig a little