A shower is a system
, not just a collection of made-for-it elements...stucco on shower walls? sure why not? Even though it's a porous cementitious compound similar to mortar and can be trowelled onto cbu or any other cement base... Trouble is that it's a rough surface and very hard to clean, as you would see when you applied it.
But, since you built a shower system all by yourself, and apart from being porous and hard to clean, the waterproofing membrane behind it will stop the water and allow the whole shower system to breathe and dry out, so you're good to go!
put a membrane there didn't you? oh-no, maybe not...
Well then, you're sorta stuck. Personally, I think you have a mess on your hands.
Ya know, I don't assume
anything much in my life anymore because when I do, I mistakenly figure I have all the bases covered and have all the answers. Seems like the more I know, the more I know I haven't got the answers...Having said that, I do
assume I have enough food in the fridge to eat a good meal tonight - but thats as much of making an a** of myself as I want to go...
If I'm wrong I'll get hungry; but when I work for others or work on my own house, I certainly don't assume anything
as I just don't know all the answers - and people pay me to know them. So I research a lot first before I do anything - to put chance on my side.
Now, and correct me if I'm wrong, first
you built a shower assuming that stucco could be waterproofed afterwards. Then you went out looking for an answer and a product.
I don't know of any product (except RedGuard) that trowels onto another surface to make a shower waterproof, even as a first line of defence against water infiltration. No paints, no coatings, nothing. And especially not a cementitious product. I mean, I love thinset - but only for certain things.
On the bright side stucco is cheap and so you can afford to replace the shower in a few months as it starts falling off the wall. So just put up another one...done right this time.
Oh...and since you would hate
to have to think about doing it over, you'll probably hate
me for saying this: Be warned: you're going to hate
your shower soon - and I'd really hate
for you to hate
me wouldn't I?