I have a 9 foot wall on the range side of my galley kitchen where I'd like to install glass mosaic tile backsplash, most likely 1 x 2" rectangles on 12" mesh sheets. I know hardibacker is not typically required in this location, however the last two feet (left side) of my wall is actually the side of a floor to ceiling cabinet with a laminate surface. This means I have a joint from cabinet to drywall that I'd like to tile over.

I'm afraid that over time where the two surfaces meet each other this will pose a challenge for the tiles as they can move, expand/contract, deflect, etc. independently and cause the tiles to come loose, crack, etc.

My first thought was to use 1/4" hardibacker as a substrate and thin set and screw it in place only for this wall so that the tiles have a solid continuous substrate to bond with. Do you think this will work?

Second question, I see lots of backsplashes where the tile sits right on top of the countertop with no room for grout or caulking. To me this seems like a bad idea as any spills or splashes seem like they would penetrate into the wall more easily. Any advice here?

Thanks.

A joint the same width as the grout joints should be there, and caulked.

If caulk that matches the grout is used it often looks very good.