That's it, that's the method that can't pass any of the tests it's been subjected to. :no:
Aside from "scratch coat" it's know also as "Jersey mud-job". It is NOT a good way to install tiles, although it'll probably work fine most of the time if everything is done just right. As the name implies, it seems to be widely used in the Jersey area as well as the GTA.
There are many methods that have been tested and used for many years. These tests have been conducted under controlled conditions by industry testing and certification organizations. On the other hand, scratch-coat has failed every time.
Among the methods that work;
A real "mud" job. A very dry mixed of damp sand and Portland, 5:1 more or less, and install over tarpaper and lath, about 1" thick works in most cases, although the "book" says should be 1 1/4" or thicker.
CBU, (cementitious backer unit), such as WonderBoard, Durock, PermaBase, HardieBacker.
Uncoupling membranes: A great way to set tiles over wood and over a slab too. Products such as Ditra, Noble's CIS and others.
I use the Ditra method when ever possible, it's a great product and I believe a premium method over the other methods under the right conditions.:thumbup: