So I understand that there is new requirements in place (or soon coming into place) for commercial steam showers. The Perm Ratings requirements I believe need to be 0.50.
I'm not sure what manufactures other than Noble Company are going to make this new requirement. The Noble membrane is rated 0.05 for the Noble Seal TS material but the KErdi membrane from Schluter has a perm rating of 0.75 I think.
It might be that Kerdi over concrete board is no longer an approved method for commercial steam showers.
I will send out a note to my Schluter rep looking for clarification. I think that Kerdi Board might pass this new requirement.
I will also touch base with Wedi and Laticrete to find out if their products will make this new requirement.
Stand by for up dates.