I am planning on building the top layer of my shower pan on top of a faulty old one. assuming I remove the old mortar surrounding the drain and it leaves me a depression deeper then 2 inches. how thick is the rest of the top mortar layer suppose to be?
The top layer should be 1 1/4″ to 1 1/2″ thick. http://floorelf.com/how-to-create-a-shower-floor-part-4 it can be 3/4″, but it has to be reinforced with metal lath beneath it attached to the substrate(in the comment section from the same source)