Can I Use Any Thin Set With Kerdi? The ICC-ES Evaluation Report On Kerdi Says You Can

[johnfrwhipple]

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.

Weird.

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???

WTF!

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!

[BobL43]

does this qualify as a conundrum or a dilemma?

[johnfrwhipple]

does this qualify as a conundrum or a dilemma?

I got Eric from Noble company shedding some good light onto the problem over on Contractor Talk. Eric mentions that drywall was removed from the TCNA book years ago so I guess we know Jim's copy is outdated and Eric also mentioned that you can get what ever kind of report you want but the code is the code and with TCNA, ANSI and TTMAC drywall is not listed.

That is not what bugs me. What bugs me is do I use regular non-modifed thinset to install ditra on plywood or can I use any thinset for ditra or Kerdi. And further more do I need to use the Kerdi Flex to seam my Kerdi sheets. We always use Kerdi Band or scraps of Kerdi or overlap the Kerdi itself.

Crazy that the ICC rules need to be followed verses the Schluter rules.

"
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." * Source

http://www.icc-es.org/reports/pdf_fi...S/ESR-2467.pdf

Jim should know - they must discuss this at the lunch table

I started testing latex primers that might work well with drywall compound. It's been over a week and I have not been given any product to use.


JW

[BobL43]

I got Eric from Noble company shedding some good light onto the problem over on Contractor Talk. Eric mentions that drywall was removed from the TCNA book years ago so I guess we know Jim's copy is outdated and Eric also mentioned that you can get what ever kind of report you want but the code is the code and with TCNA, ANSI and TTMAC drywall is not listed.

That is not what bugs me. What bugs me is do I use regular non-modifed thinset to install ditra on plywood or can I use any thinset for ditra or Kerdi. And further more do I need to use the Kerdi Flex to seam my Kerdi sheets. We always use Kerdi Band or scraps of Kerdi or overlap the Kerdi itself.

Crazy that the ICC rules need to be followed verses the Schluter rules.

http://www.icc-es.org/reports/pdf_fi...S/ESR-2467.pdf

Jim should know - they must discuss this at the lunch table

JW

I'm still trying to decide which matting to use; Ditra, Spider Web or the Noble Seal TS. I thought that modified, like Versabond was fine to use to bond the Ditra to plywood. According to what you just wrote, that is up in the air now too? One you did not mention (for tiling over plywood) is Tavy thin skin and his glue. Would you rather me start another thread on that?

[jadnashua]

The installation instructions are referenced and cover this.

Bonding Ditra or DitraXL is dependent on the substrate it is going over: they call out modified to bond it to a wooden subfloor and (I think, I'd have to reread the manual, either modified or) unmodified over masonary materials...it's pretty clear. Since Ditra is only spec'ed for floors, and the deflection issues and movement issues with wood are the biggest unknown, the use of a modified is called for, espcially since there's a moisture release path, both through the substrate and by the open channels of the membrane itself, out to the sides.

They call for unmodified when installing Kerdi, both under and over, and unmodified on Ditra over as there's no good moisture migration path between the tile and the waterproof membrane.

If you want to deviate from this, they say you need to call both them and the material (likely tile) manufacturer to come up with a suitable solution, if there is one. I have heard, indirectly, that they've allowed a rapid set modified when asked. Rapid set mortars are not likely a good solution for a DIY'er because of the limited pot life.

IF you want Ditra or Dita XL to be waterproof, then you need to band the seams, just like you do with Kerdi and that calls for an unmodified, since it is on top of the membrane. This may call for two different thinsets, or the same one and mixing it with either water or their addative to make it into a modified (probably the simplest since you don't have extra thinset in the wrong configuration - you make it up to need as required).

This is all called out in the manual. The key is: suitable and per the manufacturer's instructions.

[johnfrwhipple]

Jim I just got off the phone with Woody at the ICC. Woody tells me that any deviation from the ICC report will net a build not to code since it does not follow the ICC instructions.

The process goes like this.

Schluter puts together a system and has it privaetly tested. Then they send the test results to the ICC. Then the ICC writes up the procedure based on the private test.

The ICC is clear that the instructions must be followed.

"
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." * Source

http://www.icc-es.org/reports/pdf_fi...S/ESR-2467.pdf

Do you find it odd like me that Schluter choose to use Kerdi-Flex for the test? Did you know that Kerdi Flex is 12mil thick? Kerdi is 8mil and Kerdi band 4mil.

The ICC report also states that seams need to be banded with Kerdi Flex, not Kerdi and not Kerdi Band.

In Europe this Kerdi Flex is used in showers with Kerdi DS the 20mil version of Kerdi.

Jim you posted the information and now you choose to stay neutral. Surely the ICC report is right. And the report is not something they even test - they just write it up.

So to get back to your discussion about drywall.

If you use drywall and Kerdi and then seam your sheets of Kerdi with Kerdi - Flex your good to go. That is the proper procedure.

Thanks for the information Jim.

JW

[BobL43]

The installation instructions are referenced and cover this.

Bonding Ditra or DitraXL is dependent on the substrate it is going over: they call out modified to bond it to a wooden subfloor and (I think, I'd have to reread the manual, either modified or) unmodified over masonary materials...it's pretty clear. Since Ditra is only spec'ed for floors, and the deflection issues and movement issues with wood are the biggest unknown, the use of a modified is called for, espcially since there's a moisture release path, both through the substrate and by the open channels of the membrane itself, out to the sides.

They call for unmodified when installing Kerdi, both under and over, and unmodified on Ditra over as there's no good moisture migration path between the tile and the waterproof membrane.

If you want to deviate from this, they say you need to call both them and the material (likely tile) manufacturer to come up with a suitable solution, if there is one. I have heard, indirectly, that they've allowed a rapid set modified when asked. Rapid set mortars are not likely a good solution for a DIY'er because of the limited pot life.

IF you want Ditra or Dita XL to be waterproof, then you need to band the seams, just like you do with Kerdi and that calls for an unmodified, since it is on top of the membrane. This may call for two different thinsets, or the same one and mixing it with either water or their addative to make it into a modified (probably the simplest since you don't have extra thinset in the wrong configuration - you make it up to need as required).

This is all called out in the manual. The key is: suitable and per the manufacturer's instructions.

Thanks Jim, I did download and read the manual a few weeks ago, but can't seem to remember anything about using their own additive. going to re-read it again. This sounds like more art than the science it should be to me. And maybe that art is in the form of BS