Be very careful about using foam that does not have closed cell properties... waterproof. Wall foam will not bond and will absorb water.
I suggest A & B Foam that can be found at West Marine. It is a Marine Floatation Foam.
I do not suggest foam as a fix for delamination. You are trying to glue two layers together that have little space between... like pages in a book. Injecting foam will force the layers apart and further degrade the structure. Follow the delamination FAQ in this forum for best results. It works. I have personally done this to several boats.