Roger Taylor wrote:
We're

going to lay the tiles over existing 1x1 sq ft vinyl tile. Installer says
this is fine


You can get some perspectives on this question by typing in "tile over
vinyl" (in quotes) in the Google "Groups" search bar. Overall advice is
you should never do this, as your plastic tiles are compressible and will
result in cracking and de-bonding of the mortar or mastic, ruining the tile
job...
This story, plus the willingness for the contractor to leave the spacers in
the tile, should tell you to discontinue your dependence on this fellow.




Okay for the most part, but your wisdom concerning "compressible" blah
blah does not necessarily apply to vinyl sheet goods or even the vinyl
tiles. Tile is installed over vinyl 'sheet' goods all of the time and
is an acceptable practice by TCA standards. However, I would not
install over vinyl 'tiles', and as the OP mentioned he has some chipped
ones.