I then installed 1 4 luan on top of this and was planning on attaching the ceramic tile to the luan.
Ceramic tile over luan plywood.
Never have that under tile.
Ceramic tile stone and or cementitious backer unit installations utilizing any luan species will not be warranted by custom.
I installed 3 4 plywood over the 5 8 underlayment.
The books says a minimum of 3 8 underlayment grade plywood no 1 4 then use ditra or a 1 4 cement backer board both are installed in a wet bed of thinset.
Wood based panels such as particle board composite panels veneer faces bonded to reconstituted wood cores luan plywood and soft wood plywood all expand and contract with changes in moisture content and are not recommended as backing materials for ceramic tile.
Luan plywood is an unacceptable and unapproved substrate to receive tile or cementitious backer units cbu.
Plywood underlayment is a thin plywood material that is most commonly used under resilient flooring materials such as vinyl and linoleum sheets and tiles.
Plywood in ceramic tile installations.
I just finished prepping my 16 x 16 kitchen for ceramic tile.
If you are looking for correct then the luan has to come up.