I am finishing an underground cellar in the pacific northwest. The natural humidity ranges from 55 to high 70s. I haven't decided on whether to have a humidity control on the climate control unit I will eventually put in. My questions are 2: 1) does wide variation in humidity harm the cork by contracting/expanding it? 2) what is the high end cut off for humidity before I start worrying about mold. My cellar is vapor barriered and well insulated.