I just tried an experiment with the Great Stuff Pro and Locktite PL Premium. Reason for this was that I was concerned about using the GS to adhere my plywood flooring to the 1" polyiso that I have put down. I was afraid that the first bit of GS would be skinning over and not have any adhesion by the time I got enough laid down to "glue" a 4x8 sheet of ply. What I found was that in 5 minutes or less the GS WAS skinning and when I put the ply to it it just flattened out the bead of foam. Am I doing something wrong or missing some trick of application. On the other hand the Locktite PL Premium stays soft and sticky for a LONG time which would allow the ply to be positioned without having to fight it. Downside to that is that it needs to be loaded with weight probably at least overnight for a cure. For those of you who have used these methods do you have any advise? I have my first sheet scribed and ready to glue down I'd just rather not have to face a gluing failure.