Hello,
I was reviewing some information about different types of foam panels, and I ran across a publication by DuPont. Of course, they were interested in selling a vapor barrier product (Tyvek). The gist of the article is that XPS and EPS not only pass water vapor, but more importantly they show dimensional instability of 1-4%, e.g. a 48x96 panel may shrink to 47x94 in cold temperatures assuming a 2% shrinkage, or it may expand and buckle at high ambient temperatures. Here in SE Michigan, the temp can vary from about -15F to 95F from January to July.
http://www.dupont.com/content/dam/asset ... K25107.pdf
So, has anybody seen expansion and contraction 'in real life', with unhappy consequences?