Wall Tile Finish Adhesives

(1)  Adhesives to attach ceramic and plastic tile shall be applied to the finish coat or brown coat of plaster that has been steel-trowelled to an even surface or to gypsum board or to masonry provided the masonry has an even surface.

Article 9.29.10.3. Ontario Regulation 332/12 Building Code,   Information published by oncodes.ca for educational purposes only.

Note : Tile adhesive is the substance used to hold the tiles to the setting bed. While organic mastic is much more convenient to use, thinset adhesives actually have a higher bond strength as well as weight-bearing strength.