Discuss Adhesive thickness in the Tile Adhesive / Grout Advice area at TilersForums.com.
Thanks Andy for the infoPersonally would use a 10mm square notch trowel, backbutter/skim the tiles also before fixing, standard on walls is a 2mm spacer but some tiles can be a bit sizey so you may need 3mm and a pack of wedges to give yourself some wiggle room..check your tiles before starting.
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