Plywood alone cannot be used as a substrate under tile in showers.
Board for under tile.
Use a polymer modified thin set a type of mortar to attach the backer board to the subfloor.
The primary benefit of cement board is that it doesn t break down or expand or warp if it gets wet.
Cement board is an easily installed diy tile underlayment providing a stable dependable tile setting substrate while eliminating the complicated lath and mortar floating process.
But with many non organic shower backer boards available as alternatives there is little reason to use greenboard.
Some homeowners believe that painting or priming plywood will render it suitable to use as shower tub backer board.
Unlike wood or drywall sub surfaces cement backerboard will not rot warp or grow mold and mildew when exposed to water.
This is a distinct advantage over plywood and drywall.
If you must install over such surfaces it is best to install a backer board over the old surface and install the tile on the backer board.
If you follow all these steps you ll have a stiff monolithic crack free floor.
Tile is hard and will break or dislodge if the surface bends under the load and many wood surfaces can expand or contract negatively impacting their ability to stay level and support the weight.
Do it yourselfers can use either 1 2 or 1 4 inch cement board in certain applications while other scenarios mandate 1 2 inch board.
This provides a solid surface under the tile that prevents flexing that could lead to cracking.
Here s how to choose the best tile backer board for your project.
Tile needs to be installed on a backer board to keep the assembly stiff otherwise the assembly will flex at the grout joints allowing water to seep behind the tile and rot the substructure.
This is the industry standard most preferred by construction pros when installing ceramic or porcelain tile backer board comes in four foot by eight foot and three foot by five.
Never install new tiles over existing tiles or onto an unprotected wood or plywood floor.
Only mix as much thin set as you can use in a half hour and be sure to have solid support under each tile.
This is not true.
Cement board also provides an additional layer over a plywood or particleboard subfloor adding stiffness to the tile.
Thickness offers strength cement boards generally come in 1 4 inch 1 2 inch and 5 8 inch thicknesses.
Doesn t deteriorate when wet.
Whenever you re laying tile on a wood subfloor you need to first install cement backerboard to prevent leaks and water damage.
Lay the tile in thin set set the tiles using the same latex modified thin set and techniques used for the cement board.