Layer newspaper on the floor across the bottom of the tiled wall.
Tile over plaster walls.
Not all plaster wall surfaces will support the tile properly.
This was back in the 80 s.
Scrub the wall tiles with diluted degreasing cleaner and a nylon scrub brush.
Both painted and bare plaster allows for the installation of tile.
Adhesive grout and tile 20kg max weight onto plaster.
Or flatten walls with a latex modified skim coat product.
You would have to remove the plaster and replace it not with drywall run from a contractor who says that.
Can you lay tile on plaster walls.
Testing the wall for durability.
That is true you cannot tile over plaster if that s your plan.
Cover with cement board tape off.
Mix degreasing cleaner with water in a bucket using a dilution recommended by the cleaner manufacturer.
Also now it s been plastered you will be restricting yourself to a tile with a max weight of about 16 kg m2.
Mold does not grow on cement.
Don t use paint glue pva wall paper paste only use the primer recommended by the adhesive manufacturer of your chosen tile adhesive.
You may tile over existing tile painted or unpainted drywall plaster and textured walls.
The problem otherwise is that grout is porous and any slight crack will cause moisture and mold on any other surface.
It used to be very common to put tile up on whatever the wall was and seal the the tile.
If you re not sure if you have lead paint test kits are available.
Then rinse the wall with a water dampened.
Bring plumbing to code.
If plaster is any way compromised you should tear out to studs and start over.
Add a diverter and shower line in the wall.
I have repaired tile jobs that were over 20 years old that the tile was applied directly to regular sheetrock and plaster walls.
But with cement board.
Follow manufacturer instructions to a tee.