Tiling over paint and plaster...

[daveylard]

Hi everyone,
new here, but found it amazingly helpful in the past, and I'm hoping to tap some of that wisdom now !

I've just bought a house and as is common, am uncovering new horrors with each job.

This one is for the bathroom. I'm tiling and fitting a shower over the bath. Currently the surface is predominantly painted.
One wall is painted onto hardboard (yes really, the airing cupboard, this is where I want to fit the shower), another is painted and cracked plaster, and another is painted plasterboard.
The paint used appears to be an eggshell type, quite hard, but also where is ahs been chipped, quite brittle too.
Now, One at a time:
Can I tile onto this paint? What prep would be needed, I'm guessing scratch the hell out of it?
Second, I'm guessing that hardboard wall will never take the weight of the tiles, so I'm assuming I'll need to replace with plaster board, and secure it properly behind.
With the cracked plaster wall, my intention was to scratch the paint up, PVA it, and bond new plasterboard to it. Or would it be sufficient to plaster it directly, then tile that?

Any assistance or advice welcome, as I don't fancy ripping all that out as we are now close to move day...!!

 

[PrenticeBoyofDerry]

Roughing up the paint and priming will help the tiles adhere to the walls.
Yes either remove hardboard and reboard with PBs or board onto the hardboard.
Cracked plaster, providing the walls are sound and not failing the odd crack should not be an issue to tile to.