Your Kerdi Source - remember Dry Wall is not allowed in shower builds.
John, maybe years back when you where setting tile for a living but things have changed some. Drywall should not be used in a shower.
I'm sure Schluter will say it's OK - they are in the business of selling product. Kind of like you and your ebooks and DIY guides. You promote Kerdi and I'm sure you have done hundreds of showers that way.
The TTMAC, ANSI, TCNA and the Gypsum organaziton all say no. Call them up as well and if you get even 2 of 5 that say it's OK then maybe go ahead. Remember you need a Schluter rep to visit the jobsite or you may have warranty issues. Then there is this business of using non-modifed thinset only.
So much easier to work with pretty much any other membrane really. I notice John your switching over to Hydro Ban of late and using it to reinforce your Kerdi Seams! Smart move, I've never trusted them on any of my jobs either.
If you call Schluter ask if it's OK to use Hydro Ban on your kerdi seams - see what they say. Might make you think again about the advice you read above about drywall being OK in showers...
Just saying.
John Bridge and I are both members of the NTCA. NTCA stands for National Tile Contractors Association. On Link'din there is a members group for this NTCA association and I have a poll running now for a number of months. Here is a peak at what more NTCA Link'd in members think about drywall in the shower.
Understanding the source of your information is key when researching online. John Bridge's online store sells Kerdi and he also sells Kerdi How To Advice, this is his job. I build showers and need to pass inspections here in Vancouver and our inspectors follow the industry guidelines that do not allow drywall in showers. John Bridge has a tile forum of his own and I'm sure his presence here after all these years of barley posting is in an effort to slow down my efforts of bringing awareness to these issues of mis-information online.
Perhaps leave some drywall in a little dish of water and watch how far water can wick up the board. The only backer board I have witnessed that wicks water more is Kerdi Board. Like drywall Kerdi Board would self destruct if not properly waterproofed.
Mr. Bridge since we have your attention can you post a video of your "Magic Vortex Fold"
I have proven this wrong month after month and none of your Schluter reps or fans can show me how you did it. I laughed when I say your pictures and your holding it over a sink.
That's funny.
California like every state I believe has had these restrictions on backer boards for a number of years. Here is a city of Paulo Alto report.
http://www.cityofpaloalto.org/civica/filebank/blobdload.asp?BlobID=17678
JW