We live on the 2nd floor of a condo in Southern California and we would like to replace the old vinyl bathroom flooring (about 35 sq ft) with tile. However, our subfloor is lightweight concrete (probably gypcrete) and from my research, thinset should not be applied directly to the gypcrete subfloor. We are thinking of using a liquid membrane like RedGard to provide the necessary isolation as well as waterproofing.
We have already replaced our vinyl kitchen floor with porcelain tile about a year ago. Our contrator laid the tile over 1/4 inch cement board and we're happy with the result, but the tile is now higher than our 5/8 inch wood flooring. We would like the bathroom floor to be the same height or lower than the wood floor.
Our question is whether a liquid membrane or a glued down solid membrane would be the best solution. Any suggestions are welcome. Thank you in advance.