you ever use redguard? i used it like a big mess of it over a crack in the concrete so an isolation barrier in my floor. i suppose is its like liquid rubber... i layed tie right on the concrete its like 10+years set my kitchen floor i was stupid and didnt level the floor out, its not bad unless the sun hits it, you can seet the slight (i forget what it called) (lippage????)but ya ya know what i mean. there was major dipping in the floor... i did the best i could.... rugs help alot if i would known that area was going such a pain in ass i would have just replaced the laminate, its locked pretty good with hardie board mortor underneath and screwed down like a mother fucker im just a diy guy, its good for me. but yeah tile aint easy, thanks for the info