Geniescience
Homeowner
.... a sloped ceiling with rafters 24" OC.
...
The rest of the ceiling would be 5/8" drywall (again, because of the 24" span).
- How do you handle the transition from 1/2" ... to 5/8" ...
*This* is the reason I was planning on using 5/8" Drywall behind the Kerdi in shower area...
Any better approaches??
Since kerdi requires thinset on both sides, why not use thinner substrate instead of the exact same thickness? I don't get it. The way you are planning it, your tile + thinset + keerdi + thinest will be thick, on a 5/8" thickness.... And this is because you want it to line up?? Btw, what are you planning to do at the end, use a Schluter profile, or a special tile, or nothing?
In any case, I would make it all 12" between ceiling support members. Easy as pie. HAve you called the gypsum manufacturer to see if even 5/8" drywall will be warranteed hanging from studs 24" apart ??