Do not tile over old tile. Rip up the old stuff, remove the old mortar, lay
down a subfloor and lay the new tile. If you cheat on any of these steps you
will just have to do it again in a few months or years.

wrote in message
oups.com...
I want to put new tile on the floor (and in the newly framed in shower
with backer board etc) in our second floor bath. The tile that's there
was put down about 20 years ago. Now the threshold tiles and some
others have come up. In re-doing the bathroom my husband fixed a shower
drain leak in the floor near the sink. After fixing it he patched up
the floor with some of the same tiles and some mortar. I would like to
tile right over all this floor.
Question 1: Is it OK to tile over exsisting tile? Or should I tear up
all the old tile?
Q 2: If I tear up only some of the tiles and the threshold near the
door, the surface will be uneven where it meets the tile in the middle
of the room. Doing only the entry this way means I won't have to take
off the door to shorten it. And I won't have to take up all the old
tile. Is this OK?
Q 3: It seems that the larger the tile, the more likely it is to crack
in a second floor bath, even if a mortar base was put down first. Is
this true? or were we unlucky in getting a professional tiler who
really didn't do it right the first time?