UK Flex or non-flex adhesive for sticking backer boards to masonry wall?

[Stoobloo]

Just wondered what would be best?

The original tiles had a few hairline cracks from the house settling.

I’m planning to use flexible to stick tiles to the backer board.

 

[Tile Marble Granite]

Just wondered what would be best?

The original tiles had a few hairline cracks from the house settling.

I’m planning to use flexible to stick tiles to the backer board.

I would use flexible adhesive

 

[Ken Bruty]

For fixing the backer boards to the wall, I've never been comfortable with dot and dab fixing to the blockwork, I always recommend mechanical fixing methods solely or in addition to dot and dab, to avoid the board cracking off the wall with movement issues, especially where major building works are commencing underneath where they are knocking out structural walls, it nearly always ends in tears without extra care taken to eliminate movement, I walk away from jobs where this is not accepted.

 

[Stoobloo]

I would use flexible adhesive

Thank you. I was tending to think the same but nice to have it confirmed by someone else.