Hi all, this is my first tileing job in the bathroom. I have 600x300 mm porcelain tiles. I dont need rapid fix adhisive so have ordered Mapei Keraflex Maxi adhisive, I want to know what size adhisive trowel is best for this job and should I butter the tile first. The walls are plastered and some are new plasterboard, the walls are not too far out for a 60`s house.

personally i would use an 8mm if walls are fine and 10mm if not!

plastered walls may not be suitable for the weight of your porcelain tiles vision weigh the box of tiles before starting if possible especially if they going to ceiling height

As kilty says check the weight for the tiles that are going onto the plastered areas!
As dave says 8mm if flat 10mm if not!
As for back buttering is there a deep profile that needs filling on the back of the tile? if there is then yes you may need to back butter! or if the walls are bad then back buttering will also help

weight limit for skim plaster is 20kg per m2 or you can check this out for all substrates http://www.thetilesource.co.uk/wall-...-square-metre/.