Is it possible to tile directly over an interior block wall
by
Renea
Suggested Project Book
https://www.youtube.com/watch?v=jhxg3bCfoU0
These walls always seem to be a bit damp due to their porosity. You could try treating the wall with Dryloc concrete block paint on the inside first, and use a moisture meter to get your reading, and then ask the tile/home store if that would be ok for the mastic to cure.
Oh well if Mike above says its OK, I would give it a go.... he's a master mason