Indoor terracotta tiles on painted, rendered exterior walls - Tile Advice

[RogerAndOut]

Hello,

I have some lovely Mexican terracotta tiles (glazed on one side only) which are meant for interior use only.

I am trying to work out if I can seal the tiles with something to make them frost proof, and then stick them to a rendered exterior wall that has been painted. This is not new render, been in place many years, but it is very uneven. The garden is a fairly-sheltered courtyard.

So I'd like some advice about what products can allow me to do this. Sealants, adhesives, grouts etc, and any preparation tips please.

Thanks in advance.