Hi Sean,
On the basic level, I keep thinking that no enclosure or building method is going to last forever, that is a given...How long will SIPS last?
Funny you would ask that...
I was just having lunch with one of my friend's from "Fire Tower PE" today way up here in the Kenewa Peninsula of Michigan, and this very topic came up at lunch...
The agreed consensus (big picture) is that most of the "modern" methods of insulating architecture is (at its very best) a "big experiment" with over 90% (or more) of what most of the industry "thinks"...(or is trying to sell us)...is a "concept" at its very best...and most are greatly underperforming in the "real world" compared to what was advertised...
If we are talking "modern" (aka since the turn of the century modalities) I believe we are going to be lucky to get 50 years (20 on many of them) befor being part of a "fail system" or "outmoded," by other methods. Most are "outmoded" before we even put them in the wall compared to older and/or traditional systems...
As for foam...most of it will end up where I find it every year...chewed up in ant and squirrel nests and/or just more "icky" plastic to get rid of...I may have merit in roofs, if well done and designed for in proper application, and with "pest control/mitigation" in mind...
In the end, I can imagine clay and wood chips or even wood and mineral wool making a pretty graceful return.
This is the only way I will go from now on unless someone signs a waver and disclaimer releasing me from responsibility...Mineral wool and/or natural modalities are the way of it for me...
