Tiling over Dissimilar Materials - Tile Advice

[paya123]

I'm laying tiles over existing tiles, an additional space to the left will be tiled over as well (photo attached), I've fixed 12mm hardboard to the wall to level off the difference. Gaps have been filled with foam. Do I need to fix scrim tape with compound over the joints between the hardboard and old tiles to avoid cracks? Gaps are approx 1cm wide (filled with foam).

Any advice is much appreciated.

 

[Ajax123]

Personally wouldn't entertain it. No idea how well the tiles are stuck. No idea what the background is so no idea of weight bearing capacity. Should be a joint between substrates. not sure expanding foam is suitable filler. Not much we can be sure of really?

 

[Dumbo]

Wouldn't do it , probably exceed the weight carrying capacity of what is behind the tiles even if they are stuck well .

 

[Dan]

Get back to the original structure. Take the tiles off and the expanding foam hardboard. That's something my dad would have done lol