Plywood underlayment is a thin plywood material that is most commonly used under resilient flooring materials such as vinyl and linoleum sheets and tiles.
Ceramic tile over luan plywood.
Ceramic tile stone and or cementitious backer unit installations utilizing any luan species will not be warranted by custom.
I then installed 1 4 luan on top of this and was planning on attaching the ceramic tile to the luan.
Luan plywood is an unacceptable and unapproved substrate to receive tile or cementitious backer units cbu.
Luan is a hardwood species containing extractives sugars.
Plywood in ceramic tile installations.
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.
I installed 3 4 plywood over the 5 8 underlayment.
Never have that under tile.
It can also be used under hardwood laminate and carpet but this is much less common these days because subflooring is typically smooth enough for these materials many of which are installed with a different type of underlayment or pad.