Slightly off topic, but not much!
Even if you end up throwing 1/2 of your thinset away because you mix too much, and it starts to set before you use it, it is likely still cheaper than most mastics...
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013
Q: Can you tile over Green Board?
A: Yes you can - but will your inspector let you? You can tile over just about any surface with the right product. Here in North Vancouver you can not tile over Green Board (the drywall kind) at all in a wet zone. No No No. You can use Green EBoard that is actually white in colour and much like cement board in strength.
If you have all ready installed this Green Board and do not have the funds to upgrade to a better system at the very least apply a couple of coats of Hydro Ban or Redguard. I have asked if this is OK of my inspectors and they said it's not OK and that they would fail - but if you are just going to leave it anyway at least it is one step towards extending the life of the job.
And if you are not prepared to spend the $70 - $100 for liquid waterproofing then at the very least skim the walls out with your mastic (I assume Mastic as 1 in 2 "Box" store employees in my research suggest Green Dry Wall and Mastic) first and let dry and set the following day.
I am not endorsing any of these installs as I know the lifespan to be too short. I am pointing out the steps to improve a system all ready started and have found many people unwilling to change their work so late in the game. And if most of North America and half of the "Flooring Experts" recommended it why would I listen to these online ya hoos....
Do some more research - check with city hall - understand the life span of your install and do what's right for your family, the environment and our land fills. There is to many bathrooms in our land fills and most of them I would guess have started out down this similar path.
I my opinion green drywall is "Crap" and has not place in your shower or wet zone.
But what do I know?...
I only do this everyday for a living...
Last edited by johnfrwhipple; 08-29-2010 at 12:30 PM. Reason: spelling