QUESTION

Can you install tile over Wood - I am an art teacher and we want to make a tile ceramic sign. Can tiles be adhered to plywood for a sign? I can't find the answer anywhere on the web. We are handmaking our sign with a slab roller.

ANSWER

ANSWER - Tile can be adhered to exterior glue plywood if it is for an interior application that will not be near moisture. Other types of plywood, OSB, Particle Board, and etc. are considered too unstable to apply ceramic tile to. Wood tends to swell when it gets wet and will warp as it dries that leads to damages.

It would be better to attach the tile to a cementitious backer board or other type of tile backer board suitable for exterior or interior wet areas such as a shower.

You indicated that you are handmaking the sign with a clay slab roller to form your tiles. If this sign is for exterior use you want to be sure the clay is dense enough to be freeze thaw stable. Rule-of-thumb, 3% and less absorption in ceramic tile is considered freeze thaw stable, although it has to be verified by performing a ASTM freeze thaw test.

If you use the exterior glue plywood for an interior sign, then use a polymer modified dry set thin-set cementitious mortar that meets ANSI A118.11 designed for exterior glue plywood.

For the cementitious backer board you should use a polymer modified dry set thin-set cementitious mortar that meets ANSI A118.4.

Good Luck with your sign.