I've got these split face natural stones that come in 24 x 6 panels, and I was going to install them onto Cement Board using thinset. Checking the boards out (Permabase Plus), they contain silicates which can apparently irritate my asthmatic kid (and cause cancer it seems!).

Despite being more expensive, would Kerdi board work as a backer? I'd rather break my wallet than my kid's lifespan.

Thanks for your help.

  • I agree with sean+ , the hardi board will be under the thinset that also is full of silicate. Having a child that was regularly on a nebulizer the most import and thing will be to mix your thinset outside or use mastic the same caution on the grout. Once the product is down and sealed there are no problems.
    – Ed Beal
    Commented May 17, 2017 at 19:04

2 Answers 2


All cement products contain silicates, from the sand use in the cement. It won't be breathable unless you create dust by cutting or breaking the panels.

That being said, I don't see instructions for using Kerdi Board for flooring in the Schluter product data. It could be there and I just missed it, but I'm not seeing it. Schluter is actually pretty good about replying to emails, so you could ask them to be sure.

Another option to look into would be Schluter Ditra, another product from Schluter that is intended for use with flooring.


I called Schluter per @Sean's recommendation - they noted that using unmodified thinset was an approved means to install stone veneer onto Kerdi-Board.

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