I have been looking into acceptable backer boards for shower construction and debating for the last week with Jim over on this thread.
Jim is saying that in the USA Kerdi is approved for use over drywall. I said no that it is not and later in the week called an inspector in Pittsburgh, PA who said that most single family homes are under the building code of the IRC.
Not to get side tracked here but I just download the most recent ICC report on Schluter and here is what it says.
"Installation of Schluter® - KERDI, Schluter® - DITRA and Schluter® - DITRA XL membranes and accessories must comply with this report and the manufacturer’s published installation instructions. The manufacturer’s published installation instructions must be available at the jobsite at all times during installation.
The membranes are suitable for use with any bonded, thin-set mortar without the need for additional adhesives or primers.
The membranes are separated at expansion joints to avoid restriction of the joint movement, and the seams are sealed with flexible KERDI-FLEX." * Source
The report also states this; "5.1 Installation must comply with this report, the manufacturer’s published installation instructions and the applicable code. In the event of a conflict between the manufacturer’s published installation instructions and this report, this report governs."
Now the way I read this is that now we have Ditra, Ditra XL and Kerdi classified as primary waterproofing membranes meeting ANSI 118.1. And since the report differs from Schluter's install instructions all installs and seams need to be banded with Kerdi Flex and that any thin-set mortar can be used.
Am I missing something here? The reference to not needing primers could also mean that Ditra and Ditra XL need to be set with non-modified thin set??
So who is right? The old Kerdi install instructions or the new ICC specifications. In order to obtain an IAPMO certification an ICC report is needed. This report states that if there is a difference between the manufactures printed guidelines and the ICC report that the ICC report coverns.
And by any thin set I would assume I can use any pre-mixed modified thin set as long as I don't add any admix to the mix???
Here is a link to the report - http://www.icc-es.org/reports/pdf_fi...S/ESR-2467.pdf
This can not be right. How could the ICC screw up so badly? Or is Schluter opening the door to a wider setting material selection? I heard from the sales girl at Golden Flooring that they where working on just that. Maybe this is the way to do it.
If you follow the install specs on Schluter's website you are technically installing Kerdi and Ditra wrong if you do not use the kerdi flex for the seams. I can not wait to hear what the proper answer is.
Just when I thought I understood the process it appears it's changing.
Come on Jim - get up. This question is right up your alley!