Luan plywood subfloor is a less-than-ideal subfloor that is usually made from the cheapest plywood available. Though it can be used as a top-layer subfloor when laid on top of sturdier plywood many manufacturers do not recommend its use for tiling and other projects.
Luan plywood subfloor can be used in situations where you need to shore up an existing subfloor without spending a lot of money, and does have its value when used as an aid in installing certain types of flooring.
Luan plywood subfloors are often used when laying down hardwood flooring to help shore up and reduce any pitting, sloping or problematic subfloors. It is important to check the manufacturer’s recommendations though before installing any type of luan flooring as some specifically will not honor warranties using this type of subfloor.
A major problem with luan plywood subfloors is that any type of moisture will seriously deteriorate the wood. Luan plywood is at most one-fourth of an inch thick and is made from wood usually derived from tropical rainforests. For this reason the wood itself is not very stable and is often made of a wide variety of scrap materials that will blister severely when any type of moisture is introduced to them.
Some vinyl floor manufacturers recommend the use of luan plywood subfloors as a method of smoothing out existing floors but only when the existing subfloor is made of a hardwood that is completely dried.
We recommend that if at all possible you avoid the use of luan plywood subfloors. Because of its many problems and problematic nature you are risking having to re-do entire floor installations if something should go wrong.
Your best bet is to spend more money upfront on quality plywood before beginning your flooring project to eliminate the need to spend even greater amounts of money down the road having to potentially redo the entire flooring project.