i helped a friend install these on the outside of his tiny house. We built a frame around it the thickness of the boards/batts. We than put the boards/batts onto the wall with a few long nails. We than covered that with some 1x8 pieces of wood. The boards/batts went directly onto the exterior tar paper/housewrap.
Can be easily cut with a bread knife
Non-combustible with a melting point of approximately 1177°C (2150°F)
Excellent sound absorbency
Does not rot or promote the growth of fungi or mildew
Low moisture sorption
Chemically inert; non-corrosive
CFC- and HCFC-free product and process
Made from natural & recycled materials
ROCKWOOL® can contribute to earning LEED® points
Hi Tres and welcome to permies! I seriously considered doing this when I lived in Tucson, in a concrete block house that was a passive solar nightmare. If we had stayed, I was leaning toward aircrete at the time, but I also liked the idea of a layer of slipstraw with a lime plaster exterior.
Rockwool sounds to me like a really good way to do this, especially since it's not going to offgas toxins. You could stucco or plaster over it with a mesh to hold everything together. A vapour-permeable water barrier would probably be necessary to keep the insulation from absorbing moisture when the stucco is saturated from driving rain (and I hope you get some of that soon).
I would suggest installing a safari style wall panel after you finish the works.
I use coloured corrugated iron and insulate it with an air gap between the finished works and this new panel.
The function it serves is to shade the wall and allow air to circulate between the panels and assist in removing the suns heat which normally would be radiated onto the wall.
John Daley Bendigo, Australia
The Enemy of progress is the hope of a perfect plan