Thanks for the comments. I do have a grass mat that I had planned to use 2 sided carpet tape to install over what I thought would be a bare foam surface (after removing the foil of course). I've decided that this Johns Manville foam board will not give up its wrapping easily or without a lot of work or "cratering" the surface so it's on to "Plan B" which would be to just attach the grass mat to the foil.
I have two options. As I said, I have the carpet tape but I also have a tube of Locktite Power Grab construction adhesive. I could use them both I suppose if necessary. I'm not sure which one will be better but I imagine one of them will work.
