I am constructing a new bathroom with a tile shower, tiled base. My question is in regards to the tiled walls. I currently have cement board screwed into the studs. Do I need to put a waterproof membrane on the walls before I tile or can I just tile over the cement board?
I slathered a coat of Redguard over my backer board and then put up thinset and tiles on it. 6 years later and it's still perfect. Redguard goes on pinkish and dries what can be best described as "serial killer bloodbath red". But it works. You don't 'have to' but the time and money spent is well worth it compared to pulling it apart if/when it leaks.