Tile Over Plywood Vs Cement Board

Screws secure the cement board to the wall studs.

Tile over plywood vs cement board.

A 3 4 inch plywood subfloor on a joist structure with 24 inch spacing needs the extra thickness of cementboard or the floor will flex and the tiles will crack. As a result the grout lines and the tiles themselves can crack and become damaged. Plywood is porous and not designed for use with most of today s latex based thinset mortars. The installers tore out the old tile which was installed over plywood.

The tile runs from our utility room through the kitchen hall bathroom and foyer. Uncoupling membranes aren t recommended for tiles smaller than 2 inches square and should not be used when covering old hardwood flooring due to adhesion problems. Instead of laying tile on a plywood subfloor it s better to lay a cement board on top of the plywood subfloor first. This is a distinct advantage over plywood and drywall.

Cement board also provides an additional layer over a plywood or particleboard subfloor adding stiffness to the tile installation to help prevent cracks. In addition to this tile can not properly adhere to wood the way it does to concrete. In this highly convenient inexpensive and popular application a moisture barrier of 4 or 6 mil thick plastic is installed directly over the wall studs. When the tile is laid on top of a plywood subfloor the plywood will expand over the years.

The best argument when determining whether to use plywood or cement board under tile is in the adhesive process. The primary benefit of cement board is that it doesn t break down or expand or warp if it gets wet. Then the cement board is installed on top of the plastic sheeting. Ok so we had 603 square feet of porcelain tile installed through the first floor of our home.

Cement board is a type of underlayment that is now standard for most tile installations but particularly for floor tile. A number of different types of substrate are used for tile including plywood. But a number of precautions must be taken to ensure a successful installation. Even if you use a waterproof underlayment membrane the floor will still be either 1 4 or 1 2 higher than the subfloor plus the thickness of the tile and adhesive.

Cement backerboard is designed specifically for this use. While most floor tile these days is installed onto a layer of cement board or similar backerboard it is possible to lay tile directly over plywood. While i prefer using 1 2 cement backer board over a plywood subfloor you may be able to get by with 1 4 backer board instead.