©2015 Green Building Advisor. From The Taunton Press, Inc., publisher of Fine Homebuilding Magazine.
I’m going to be converting my crawl space to a sealed, conditioned space. The concrete block walls will be insulated with rigid foam. I’ll be using TherMax, as I understand that unfaced rigid foam does not meet the ignition barriers of the IRC. I am also planning to use spray foam to air seal and insulate the rim joists (per Fine Homebuilding No. 189 , September 2007). Interestingly, I’ve never seen any discussions about ignition barrier for the foam for the rim joists. What’s the story here? Also, living in a moderate-to-high termite risk zone, I recognize the need to leave the top 2-3” of the block wall uninsulated and exposed, as a termite inspection strip. On the other hand , leaving that strip, as well as the 2-1/2” strip along the top of the block wall (I have a 2x6 sill plate on an 8” block wall) seems like an incomplete insulation job. Since termite inspection would typically occur no more than once a year, wouldn’t it make sense to make some sort of removable rigid foam strips to fully insulate the wall?