I know from my previous question that in most cases a cement board of some kind needs to be used. However, when the Kerdi membrane system is being used behind the tile, is it still necessary to use a cement backer board?

1 Answer 1


Schluter says that behind the Kerdi membrane a solid backing needs to be used. They define a solid backing as :

  • gypsum wallboard
  • cementitious backer unit
  • fibercement underlayment
  • fiber-reinforced water-resistant
  • backerboard/underlayment
  • coated glass mat water-resistant gypsum
  • backerboard
  • portland cement mortar bed
  • concrete
  • masonry

Found this in their Shower System Installation Handbook here. Link : http://www.schluter.com/media/ShowerHandbook.pdf

  • Add a link to the source of this info to make this the perfect answer.
    – auujay
    Jan 24, 2011 at 21:28

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