Install Ceramic Tile Over Plywood Subfloor

There are two materials commonly used for laying ceramic on plywood or osb that are applied before the tile.

Install ceramic tile over plywood subfloor.

Concrete board concrete board also called backer board comes in 1 4 and 1 2 thicknesses and is usually sold in 4 x 6 sheets. If you find hollows and valleys you must fill them with a self leveling underlayment. Fill seams in the subfloor with caulk. The tile industry recommends a sub floor of at least 1 1 4 thick.

Lift one sheet leave the rest in place and spread thinset directly onto the subfloor filling the area left by the sheet use a 1 4 x 1 4 notch trowel. A successful tile installation project requires a level surface. Keep in mind when building up the thickness of your sub floor to overlap the seams of the different layers of plywood as this will also help stiffen the floor. 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.

The plywood will expand and contract at a different rate as the tile causing cracks to develop in the grout lines or tiles over time. While tile can be laid on plywood do not install tile directly onto the plywood subfloor itself. If there is too much deflection in your sub floor then tiles may pop loose over time. For example if you install resilient tiles or sheet flooring over a subfloor any bumps dips or voids in the subfloor may be evident in the finished flooring.

Lay down a vapour barrier overtop the concrete pad then fasten 3 4 inch plywood using a ramset to the concrete pad through the vapor barrier then install the heating system to the plywood followed by applying the self leveling mortar over top the heating system and plywood and finally installing the tiles over top that. Underlayment covers subfloor flaws for the best possible results. Once you have filled the space place the sheet down onto the thinset. It should be fastened to the subfloor using thinset and then screwed down every 10 square.

Plywood underlayment is typically needed when a floor material must have a very smooth flat surface. Mix your thinset according to the instructions on the bag. Install the sheets one at a time. Use thinset with a higher latex content thinset is the wet base that you first trowel on the plywood to make the tile stick.

On a plywood subfloor you need either a layer of cement backer board or an underlayment membrane like custom building products wonderboard and redgard between the subfloor. 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.