Can the wall with foam be plastered on the outside?
There are several projects carried out in Poland where external façade solution was used (closed-cell foam and plaster), however it is not a commonly used technology. The difficulty of this type of connection is related to the choice of suitable plaster, which must have proper adhesion (e.g. lathing mesh is helpful). Nevertheless, levelling of the plastered surface can be the biggest problem due to the irregular foam structure.