The best underlayment for ceramic tile is cement or cement board, which ensures there will be no movement that can loosen or crack the tiles. But you may run into circumstances where you have to tile directly over a wood sub-floor (if the floor opens directly to another floor and you don't want to raise the floor level, for example). In those cases, you can lay the tile over wood with a little extra preparation, as long as the wood is solid and flat.
Things You'll Need
- Screw gun
- 1 3/4-inch wood screws (galvanized)
- Floor leveling compound
- Chalk snap line
- Carpenter's square
- Tile mortar
- Notched trowel
- Floor tiles
- Tile spacers
- Tile cutter
- Grout trowel
Walk slowly over the wood floor with your screw gun and screws, looking for any areas that move. Sink screws where necessary to stop all movement of the boards. Drive the screws in deeply enough that the heads are below the surface.
Mix a batch of floor leveling compound according to the instructions. The compound should be as thin as water. Pour it slowly over any gaps, crevices or holes in the wood floor, letting it level out completely. Allow the leveler to set overnight.
Use a chalk snap line to divide the floor into four squares, with two wall-to-wall lines that intersect in the middle of the floor. Use a carpenter's square to adjust the lines so they're 90 degrees off each other.
Lay a layer of tile mortar over a few square feet at the center of the floor with a notched trowel, covering the intersection of the lines. The lines should still be visible through the mortar.
Press four floor tiles into the mortar, using the intersection of the lines as your guide to position them. Put spacers between them.
Spread more mortar and continue laying tiles, building out from the middle toward the edges of the room in a grid. Use spacers throughout. Cut the tiles as needed at the edges of the floor, using a tile cutter.
Allow the mortar to set for 10 to 12 hours. Pull out the spacers. Grout the floor with a grout float, forcing the grout into the spaces between the tiles and wiping off the excess grout with a dampened sponge. Let the grout set for two days before walking on it.