AP Foil-Faced Polyiso Sheathing board recently earned ICC approval as an air- and water-resistant barrier. A 1-inch layer, the board has a reflective foil face on one side and a non-reflective face on the other. It offers an R-value of 6.5 per inch and is Energy Star certified. Cost: $12 to $15 for a 4x8 board. Johns Manville, 800.654.3103, jm.com
