My 1st Job Uneven backerboard. Advice?

[Screwless]

Hi
Ive recently embarked on a mental mission to tile my bathroom despite no prior experience. I’ve tried my best to prepare the tile surface. so, stripped everything back to bare brick, primed and stuck elements backer board on. Much ti my annoyance, I’ve not managed ti get it perfectly flat vertically. It’s out over a span of 1.8m by 3mm. What’s the best way of dealing with this? Adhesive on walls with a notched trowel and back buttering on tiles?
Thanks in advance for any help offered.

PS in the internal corners, is it best to leave an expansion gap? If so, any general recommendation

 

[eddcottee]

That's not too big an issue mate, just sort it out with your adhesive. What size are your tiles? You might be wise to use levelling clips and wedges to get everything bang on. Yes, trowel the adhesive onto the walls and then back butter the tiles.

Yes, you need to leave and expansion gap in the corners of a few mm. Then rather than grouting that joint, run a bead of Silicon along it.

 

[Screwless]

That's not too big an issue mate, just sort it out with your adhesive. What size are your tiles? You might be wise to use levelling clips and wedges to get everything bang on. Yes, trowel the adhesive onto the walls and then back butter the tiles.

Yes, you need to leave and expansion gap in the corners of a few mm. Then rather than grouting that joint, run a bead of Silicon along it.

Hi mate, many thanks for responding. The tiles will be 600x300. Intention was to use levellers. Not decided on the exact ones. But, plain white glazed is my preference. I'll have to stick to ceramic as one of the walls is plastered blockwork, so weight restriction is a major limit. 20kg sqm? Any tips on what to look out for when selecting tiles? Happy to pay more if it's worth doing.
Cheers.