How to Tile a Floor Over Plywood
- 1). Start with a clean surface. Sweep the floor and vacuum any dust from corners and the edges of the room.
- 2). Secure the plywood to the floor joists by driving corrosion-resistant nails through the plywood into the joists below. Set them slightly lower than the surface and fill the holes with gypsum leveling compound, smoothing them with a putty knife.
- 3). Lay cement backerboard. It comes in 3-by-5-foot sheets, so you may have to cut some to size. If you have to cut it, use a circular saw with a masonry blade, and do all your cutting outside wearing an approved NIOSH/OSHA dust mask to prevent yourself from inhaling the dust.
- 4). Use corrosion-resistant screws to secure the cement backerboard to the plywood. Tim Carter of Ask the Builder recommends setting screws every 8 inches on center.
- 5). Tape the joints with drywall tape then fill them with thinset. Take the time to feather the thinset out from the center so the surface is smooth and level.
- 6). Do a dry run with the tile before setting it. Lay out the tile on the backerboard without thinset. This will help you see where you'll have to cut tiles to fit. Make sure all your cut tiles are along the edges of the room and, if possible, hide them under appliances or furniture.
- 7). Mix the thinset. This Old House recommends mixing a latex adhesive into your thinset instead of water to improve durability. Chuck a mixer into your power drill and mix the thinset. As a general rule of thumb, don't mix more than you can use in two hours.
- 8). Spread a coat of thinset with a trowel. This Old House recommends applying a thin scratch layer with the flat edge then letting it set for a few minutes before applying another layer using the notched edge. Apply the thinset holding the trowel at a 45-degree angle.
- 9). Use a straightedge as your guide to lay the first tiles. Use the first row of tile as your guide for the following rows. Lay one tile and press firmly with your fingers spread around the center of the tile. Give a slight twist of the wrist to press the tile into the thinset. Work from the center of the room out toward the walls, as This Old House recommends.
- 10
Let the thinset set overnight and apply grout in the morning. Apply grout with a rubber-bottomed float held diagonal to the joints. Working in diagonal strokes will prevent the float from lifting grout from the joints as it passes over them. - 11
Let the grout sit for 15 to 20 minutes then wipe off the residue with a damp sponge. Rinse the sponge frequently in clean water. Let the grout sit overnight and wipe the floor clean with a dry rag in the morning.
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