In this video the guy is installing a fiber glass fabric before the second layer of insulation. I think I have seen something similar in the Kerdi videos. Is this something I should use with cement board ?

  • I don't see the fiberglass insulation in this video. Do you mean the tapings?
    – r13
    Commented Oct 10, 2021 at 21:45
  • finer glass fabric this is what he calls it in the video
    – MiniMe
    Commented Oct 10, 2021 at 21:52
  • It just sealing the drywall joint and make it stronger. I am not sure you need that for cement board though.
    – r13
    Commented Oct 10, 2021 at 21:57
  • Sounds like a good idea though
    – MiniMe
    Commented Oct 10, 2021 at 21:59
  • Well, turns out it is not a bad idea. See this video. (Around 7:20) bing.com/videos/…
    – r13
    Commented Oct 10, 2021 at 22:46

1 Answer 1


Yes it is a good idea to use on any joints and changes of plane. Each company has their own now including mapei, laticrete, and custom building products etc. but they should be interchangeable for any of the liquid membrane products.

This isn't the same as the kerdiband which is installed with thinset and the product itself is the waterproofing layer

Be careful of buildup in the corners especially if you taped and filled joints in the backer board board with thinset before waterproofing

  • I can't find that fiber glass at Home Depot in Canada I opted Kerdi Band instead youtu.be/48pwER0GFSs?t=1112
    – MiniMe
    Commented Oct 16, 2021 at 22:46
  • Kerdi band is not the same as this fabric and shouldn't be used with a paint on membrane
    – redlude97
    Commented Oct 18, 2021 at 2:06
  • I ended up using Kerdi band because I could not find that fiber glass
    – MiniMe
    Commented Nov 13, 2021 at 19:19

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