Question: is mapei premium mortar modified?
Answer: MAPEI's Type 1 and Premium Mortar should not be used under cement board. ... If the cement board manufacturer recommends a polymer-modified mortar, use MAPEI Porcelain Tile Mortar or Ultraflex™ 2. If the cement board manufacturer recommends a non-modified mortar, use MAPEI's Uncoupling Membrane Mortar or Kerabond™.