Can Tile Be Installed Directly Over Exterior Plywood?
Exterior plywood contracts and expands, which makes it hard to bond with other materials. In order to install tile directly over the exterior plywood, you will need to use a special bonding agent in order for it to hold up. You will need to purchase a polymer mortar that meets required standards. An alternative to polymer bonding is Wonderboard or a similar product, which allows you to apply it directly to the plywood with adhesive, and then tile on the other side. Either method will give you a stable surface for the expansion and contraction during climate changes.