yeah that is what I ment, icf needs to have a waterproof membrane for longevity. otherwise it eventually soaks and loses it's r value, however, I don't really think this is a necessary for your application. it was more of a quick pool build not so much as an insulation factor. still impressed by this.Do you mean the icf panel? I probably should have but I didn’t. There wasn’t any room between the icf and the dirt wall. As far as sealing the concrete I plan to do that but have to wait for the concrete to cure longer. I have used cure n seal on concrete in the past but the concrete specialty store was out and thought it might make the deck more slick.