HI, I started my 32 x 36 Alan Scott type oven a couple of months ago and all has gone well for the most part. I built a substantial support to support the hearth slab poor not thinking I would have to remove it. I assumed that the 4" firebrick plus 3-1/2" slab plus 2-1/2" of vermiculite/ Portland the plywood under would be OK and I could leave it in place. I did my first fire a couple of day's ago and wow, this plywood is hot! What are the opinions as far as removing the plywood and supports and any idea's for additional insulation I could put under there?