I recently discovered foam form construction and have found it fascinating. It is like building with large legos....looks like it simplified construction for the layman/diy person. I know that my first question may seem diametrically opposed to the permie idea...has anyone considered using clay, cob, etc in this kind of form? My second question, is it possible to make forms like this out of pressed straw, hemp or some other natural material?
Rammed earth involves forms. They're wooden forms, not foam, and they're removed, not left in place.... but as far as a natural version, yes. People have doing it for a very, very long time, and pretty well have the kinks worked out. http://en.wikipedia.org/wiki/Rammed_earth
As far as using earth or clay in a foam form, the first problem that comes to mind is this:
Concrete is suitable for use in a non-permeable, non-removed form, because concrete hardens by curing. Earth hardens by drying, so a method that doesn't allow the water out of the earth isn't going to lead to a useful structural component.
This is a rapidly developing industry...some good...many not so much...all growing each year...
Some of the product lines are very 'low tech' and natural.
ICF are, in general, not the great thing they are cracked up to be. Having followed them since they came to be. I have even corresponded with many of the developers that now are switching over to more sustainable materials and methods that do not have the challenges that the original ICF system presented.
As for foams, some are working on soy based but this is coming from 'big ag business' and not any better than what we see (if not worse) than the petroleum industries. As for a "foamed" system that has promise I would look into magnesium oxide and related "aircretes."
Durisol insulated concrete forms is one of the industry leaders at the moment, yet again is very heavily industrialized compared to actual...natural building methods that are superior.