[dmun]

I put a vent above the vermiculite layer of my insulation. They make vents that are the size of a single brick, that's what I used. I figured that atmospheric moisture that accumulated in my insulation when the oven was cold could use a place to vent off. Also, my superstructure is wood, and condensation on wood is a no-no. That's why your house attic is vented, top and bottom, outside the insulation, to keep the rafters from rotting.