On vacation and finally building my bench. On the downside, winter decided to show up in central Illinois this week. 5-7" of snow with sub-zero temps oh, why didn't I get on this sooner?! The bench is coming along well and I'm looking into using cam-6, which is used for road underlayment @ about $8/yard. I'm still planning on using urbanite under the duct, filled in with cob to reduce air gaps. I have it raised up on brick rows, Bonny style, to tap into passive air flow. The hollow cores on the block that I'm using for containment, I'm going to fill with either cob or vermiculite- (I got the block CHEAP). My exhaust configuration should be a winner as I'll have the vertical stack through the roofline. But since old man winter decided to show up, I might have to wait. The roofer down the street who was going to do it this week says ill have to wait till the temps get to at least 25 degrees to do the flashing. In the meantime I might just run a temporary stack out of the upstairs window and just pack the space around the duct with rock wool to keep from freezing or burning my barn down. Will post further updates and pics!