There is a very good article in the American magazine 'Fine Homebuilding', issue no. 225, March 2012, page 55. A builder in Massachussets who did a 'deep-energy retrofit' on his house and office/ barn conversion sixteen years ago decided to update the barn conversion. He stripped it down again and analysed the performance of the various components. He had wrapped the barn in a single layer of EPS taped and mastic-ed at the joints. The boards shrunk, the tape /mastic cracked, and the joints opened. He could see this starting in the first winter with frost melting on the joint lines. He had used a single layer of XPS sealed with Tyvek tape on parts of his main house, so he removed the weatherboards and investigated that, and found that the joints and tape were in perfect condition after 16 yrs.