Has anyone ever done a room under a garage?  We have a customer who currently has one that wasn’t done properly, the garage slab has cracked (typical for concrete) but there was no water barrier installed incase of leaking so mould has started to form.  We are thinking of using Platon (foundation exterior wrap) to cover the ceiling and the walls with drainage through the slab into the gravel underneath.  Looking for any other ideas or suggestions that might be better or easier to do