Thankfully our customer hired someone to remove the existing ceramic tile saving us the effort. The ridges of old mortar bonding the previous tile installation needed to be sanded down to a smooth, flat surface. My brother Steve has that honour.
The old concrete was dry and porous so I decided to use a sealer over the entire area. Probably not necessary, but if it helps to create a better bond ... why not?
The Ditra is being installed with a modified thinset mortar.
After centering the rooms and snapping chalk lines for my "grid", I begin to set the tile using an "unmodified mortar".
These are 20" tiles. A straight edge or level helps keep it all flow nice and even from one point in the room to the next.
The step is ready for tile.
I've used Schluter's RONDEC to trim the edge of the tile for my step. RONDEC has pre-manufactured corners for this application.