How to Repair Floor Tile

Ron's first stop of this HouseCalls episode is in Takoma Park, Maryland, where Matt and Sue Smith are having a problem with some ceramic floor tiles. Several of the tiles have become loose and the Smiths have asked Ron if he would help them figure out the cause of the problem and then lend a hand in the repairs.

Click Here For a list of what you will need in order to complete this project.

Ron explained that when many tiles are coming loose from the floor at one time, there are usually only two possible reasons. Either the mortar holding the tiles to the floor has failed, or the floor itself is moving or flexing. The first thing that Ron helps Matt Smith do is to determine the cause of his loose tiles.

1. Check sub-floor:

• Since most of the loose tiles were in a high foot traffic area, Ron first wanted to check the sub-floor, to see how thick it was. Tile needs to be set on a sub-floor that is no less than 1-inch thick for proper support. Ron suspected that the plywood underneath the Smith's tile was only three-quarters of an inch thick. The only way to tell for certain was to use a hand saw to cut a little piece of the stair away to see the edge of the floor. In this case the sub-floor was, indeed, laid on ¾ " plywood.

• Ron created a model with a piece of tile, and a piece of plywood to show us what happens when the sub-floor underneath tile is too thin. As the plywood starts to flex back and forth, one of two things happens. Either the tile will break, or it will pop off.

• It would be both time-consuming and costly to create a permanent fix to this problem. Matt and Ron would need to remove all of the tiles in the room, add one-quarter inch to the sub-floor, and then re-tile the whole area. That was more than Matt wanted to take on, at least for the time being. They decided to patch the damaged floor. Ron reminded Matt that with patching alone, they might see only a temporary fix to this frustrating problem.

2. Remove loose tiles:

• Begin by removing the loose tiles by carefully prying them up with a putty knife or pry bar. If possible, try to re-use as many of the loose tiles as possible, but many will probably have a heavy coating of rock-hard mortar on the back, which is impossible to get off. It is extremely helpful to have a leftover supply of tiles.
• After removing the tiles, scrape the mortar from the sub-floor and vacuum up the fine dust and debris.

3. Mix mortar:

• Ron recommends using a thin-set mortar to lay the replacement tile. Select a mortar that has an acrylic, or latex additive, which will help the tiles bond better to the plywood. Alternatively, a liquid acrylic can be added to regular thin set mortar instead of plain water.
• Pour the mortar, which comes in powder form, into about a gallon of water. Ron mixed the mortar using a paddle mixer powered by an electric drill.

• After mixing, let it rest, or slake, as it is called, for two or three minutes. Remix it very quickly after it has been allowed to sit and it is ready to use. The thin-set mortar selected for this project was also fast setting so they only had about twenty minutes to use the mixture. If you do not need a fast setting mortar, you will have more time to work with the product and have less need to rush, which is probably best in most cases. A regular setting mortar requires between 24 and 48 hours to set before grouting.

• Begin with the straight edge of a quarter-inch notch trowel, hold it at a thirty-degree angle to the floor surface and spread the mortar, pressing it firmly into contact with the surface. It is very important to create a strong firm contact with the plywood, so make sure that all of the crevices and depressions are filled with the mortar.

• Turn the trowel over and make a single pass over the surface with the notched edge to create furrows. This will provide the uniform thickness necessary to lay a level floor.

• Drop each tile into position and twist it back and forth just a little to create a firm bond.
• After laying all the larger pieces, you will need to cut smaller shapes to fill in along the edges of the room or in this case to cover the face of the steps.

• Cut these smaller pieces to size using a water-cooled tile saw. (These can be rented at your local rental yard). The saw sprays water on the tile to keep it cool and prevent cracking. This water can easily wash off pencil and pen marks from the surface of the tile. A pencil or ballpoint pen mark on masking tape, however, will not wash off so Ron recommends applying a piece of tape to the tile before marking where to cut.

• To make sure the tiles are firmly in contact with the mortar, tap them gently with a mallet, using a block of wood to distribute the force of the blow, and protect the face of the tile.

5. Grout:

• Normal thin-set mortar requires 24 to 48-hours to dry before you can begin grouting, but the rapid-setting mortar is ready for grouting in just two hours.
• Use the float to force the grout into the joint between the tiles. The grout needs to fill the space all the way to the bottom so you should use a fair amount of pressure. Then, tip the float up at about 45 degrees, and rake it diagonally across the face of the tile. The reason for the diagonal is to avoid scooping the grout back out or the spaces between the tiles with the float.

6. Clean off tiles:

• When the grout begins to get firm, use a damp sponge to wipe off the excess from the face of the tiles, while changing the water frequently. After three or four cleanings, allow a thin haze to form on the surface. Then buff the tile with a clean, dry cloth.

RESULTS:

It was discouraging for the Smiths to learn that a permanent solution to their loose tile problem was going to be very costly and time-consuming. But with the new skills Ron taught Matt, he is ready and able to take on the next repair job if it becomes necessary. And with the special additive in the mortar they used, hopefully future repairs won't be necessary.

And thank goodness the Smiths had saved some extra tiles. This is something you should always remember when you put in a new tile floor. Without those tiles, Ron probably could not have been much help with this project.