It looks like the majority of the wood was normal, only a part of it was rotten. Possibly so as not to make anyone suspicious. They had moved the slightly rotted parts away, but now it's fully rotted through, the foreman was surprised, he hadn't seen it happen. Alucard says it smells like flesh, which is very creepy, and also confusing. We're trying to see if we can go to Solvunn ourselves and follow the scent.

He can probably describe it to someone if you end up having someone with advanced senses over there. If not just have them check the grain, if a section taken from Solvunn is rotted, regardless of smell, it would fit in with this.