Heroes 6 - Discussion

A sawmill underground doesn't really look good, to be honest.

That's why there's a terrain type in the fifth game called "tree roots," as well as various strangely shaped trees, which, logically, they would cut at those sawmills. The only thing is that they don't think about the design until later, so it's not uncommon to see a sawmill in the middle of a desolate underground corridor.