True I just worry about stuff thats all.....ive had two tilers come out.....one was through this forum actually and he did the laitence removal for me .....he mentioned uncoupling but didnt say do that....just to prime and stuff whatever you use....and maybe go for anyhyfix adhesive......the tiler im using wants to use ultra tile fix.... either s1 or s2....said hes used for years with no problems....it says on the bag its fine for these types of screed too....so I guess well go for that...hes the pro afterall.......im just trying to avoid any future issues.....thats all