a layer of 2K PU parquet glue flocked with peat. It's a common method applied in Europe, but I'm not sure about the US.
Funny - this is the 2nd time this week I've seen this glue mentioned for vivaria, but also only the 2nd time in my life. (I'm an American, presently living in the USA.) No, I do not think it is a common method over here (yet?). Can you hazard a guess how long it has been in use there? No toxicity problems I assume? Perfectly waterproof once cured?
It's an interesting consistency - looks very workable, not too runny but fluid enough for easy spreading. For vivaria, do you just apply it with a decent paintbrush, or what? I saw some online videos where they were using a typical grooved flooring trowel, for installing "non-floating" wood laminate flooring.
Thanks very much. Gorgeous creation by the way.