That is one big stack of SIPS, or Structural Insulated Panels. I have never seen them so thick as that one on the bottom, a full 12 inches and rated at R-52. These are from PorterSIPs, and are sandwiches of OSB (oriented strand board) and EPS (Expanded Polystyrene). Expanded polystyrene is not without problems. As Alex Wilson points out at En… Read the full story on TreeHugger
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Super SIPS Get Over R-50; That’s A Lot of Insulation!