I have heard of foam. The idea being you sticky side of the foam to the layout base and it raises the track slightly. Then you don't need to nail or screw down the track since the foam weather stripping keeps it from sliding around.
I saw this suggested in tinplate times or somewhere similar but have not yet tried it myself.
Not sure how it can raise the base when foam is so soft and compressible. Unless you are referring to a different type of foam, maybe closed cell foam?