What Type of Plywood Can Be Used Under Ceramic Tile?

Plywood should never be used under ceramic tile. The proper material to use is a cement backer board. If it is completely necessary to use plywood, make sure it is an exterior grade of plywood so that it resists moisture. Sometimes ceramic tile is applied to plywood with a mortar bed.

Types of Plywood NOT to Use

Some types of wood that should not be used as a sub-floor material are: chip board, vinyl flooring, particle board, luan, OSB, tongue-and-groove planking, and hardwood floor surfaces. These materials are not acceptable or stable enough to be used as a sub-floor material under ceramic tile.

No Plywood

Ceramic tile should not be laid over plywood because plywood has a smooth surface. Plywood also swells and warps when exposed to moisture. That could lead to movement or cracking of the tile.

Plywood Recommendations

If plywood must be used, then use double-layered, exterior plywood that measures 1 1/8 inches thick. Attach plywood over floor joists. Don't forget to leave a 1/8-inch gap between the sheets of plywood to allow for settling and swelling. Leave 1/4 inch around the edges of the walls, cabinets, door jambs and fixtures.

Ideal Material to be Used

The ideal material to use under ceramic tile is cement board, sometimes called backer board which is moisture-resistant.

Installation of tiles

Once the sub-floor material is affixed, install tile using a latex modified thin-set mortar. Then grout.