Drywall is not allowed in showers with Kerdi!
Hear we go again.
Drywall is not approved in any shower - covered with Kerdi or not. Use cement board, Hardi board or Green EBoard (not green drywall). Anyone telling you that it's OK to use drywalll in the shower is in the business of selling Kerdi, not building showers.
The TCNA also recommends drywall only in dry areas. No where does it state Kerdi can be used in a shower with drywall.
The drywall industry does not promote it.
Mapei does not promote it.
Custom Building Products do not promote it.
Laticrete does not promote it.
If you really want to use drywall and really believe it's OK call Schluter and ask which thin-set to use. Ask them which primer to use. When they talk in circles and say things like we don't recommend one specific brand then call Custom Building Products, Mapei or Laticrete and ask them. They will tell you drywall is a mistake in the shower and outside industry guidelines.
Only Schluter will do this.
Now you have the business of only a five year warranty. If you must use Kerdi - use Ardex setting materials. This will double your warranty to ten years.
Now if you want a 15 year warranty you can build your shower with Mapei's products - I love them and use them all the time.
Or you can use Laticrete or Custom Building Products and get a 25 year warranty.
In all these extended install warranties one thing is common - there is no drywall in the assembly.
It was recommended to me that if drywall where to be used in a shower that a Schluter rep should inspect and document to job. What a pain. Just use a proper backer board.
Drywall is ____ and has no business in your shower renovation's wet zone.
Once built make sure your tile crew flood tests it. Have your requested this?
Also tell your crew you expect all TCNA specifications to be followed for this build. Good luck.
Can drywall be used in your shower renovation with Kerdi - Answer. No.
"...At the same time, not all manufacturers of
gypsum board recommend their product be used in a B422 installation. Thus, the
Handbook leaves the determination of a suitable membrane/backer board
combination up to the membrane and backer board manufacturers to declare and up
to the design professional to select/specify...."
She left out the part about the setting material company's opinion.
So if you can find a drywall producer who allows it.
Then find a waterproofing manufacture that does (only Schluter to my knowledge)
And find a setting material supplier that thinks it's OK then you might have a leg to stand on.
And you forgot to mention you also need permission from your local building inspector. I have brought all this info down to them and here in Vancouver the answer to the question of "Can I used drywall in a shower if I cover it with Kerdi?" is NO.
No you can't.
No your not allowed to use drywall in a shower.
No. No. No.
The fact that a company selling a membrane has no say over the local building code departments.
What a crazy idea using drywall in a shower. If you want Kerdi - use Hardie backer. use Cement Board.
Place a piece of drywall in your kitchen sink for ten minuntes (full of water) Place a sheet of concrete board in at the same time.
Take them out.
Try and snap the cement board. Try and snap the drywall.
Why anyone promotes this is for no other reason than to sell it as a cost saving's measure. It's not better for your shower it's cheaper!
It should register with anyone researching this point that only one company says it's OK. And they don't even install it that way in the country it's made!
Think about it.
"....Many in the industry feel that building code prohibits the use of gypsum
board in wet areas, even when a waterproof membrane is applied to the surface.
However this is a matter of code interpretation, with the actual code language
somewhat ambiguous, and with some feeling the code only prohibits direct bond of
tile to gypsum board in wet areas....."
Interpepretation? The local code here outlines what boards can be used in showers. Drywall is not on the list. How do you get that wrong? Drywall is not on the list. So what is the confusion Jim? Seriously Jim do you own shares in Kerdi? I thought they where a private company.
Drywall is not allowed in shower construction - period.