Salem

Does the 5 clear tiles area around a timber pile to reduce the mold mean a dug up/bare or paved area or does the biome growing back in that area also increase the mold risk???
Biome growing back would mean herb/forage spawns... Will they icrease the mold risk???

i wondered that too, i don't want to pave all the area but even with a cleared area i sometimes get molded boards, don't know if there is a rng/ base chance or if vegetation is the reason

There is always a random chance that there are moldy boards even if you do pave or place them 5 tiles from all things away.
To get more moldy boards is only be affected from things that have a collison box. That mean, that per example Claimstones or Boundry stones does not affect the chance for moldy boards, because you can walk through.
This means that spawning plants also doesn't affect the chance for getting moldy boards.