Super SIPS Get Over R-50; That's A Lot of Insulation!
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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. Tom Lent of the Healthy Building Network notes in Environmental Building News that "Polystyrene depends on some highly toxic chemicals, including known carcinogens, from the beginning to the end of its life cycle." Alex Wilson describes the process: It is made by combining ethylene (made from natural gas or petroleum) and benzene (made from petroleum) to produce ethylbenzene, which is then dehydrogenated to form styrene in a process that produces byproducts benzene and toluene. The styrene is then polymerized to form polystyrene. Also, it is treated with the brominated flame retardant HBCD, which we think should be banned. Not to mention that the OSB sheathing is an excellent source of formaldehyde. But R-52 saves a lot of energy; that's Passivhaus territory. ... Read the full story on TreeHugger