Rotted out every 16" on the back only, proof positive that the rot only occurred at the point where water was allowed to enter the wood deeply, namely at the fastener splits. This gutter was spaced away from the fascia with 1/2" wood strips but that did not stop this from happening. I found this first floor gutter under a canopy of trees. It was full of debris and water. The small leader outlets at the very bottom were covered over with tree litter. In this photo the gutter is now dried out. Rotted wood holds water like a sponge, so once rot begin it helps aid further rot by helping the wood in the infected area say wet.