Many buildings in Europe have tile floors that are 1000s of years old that are pristine condition. In the United States, however, tile floor often crack after less than 10 years. What did the ancient Europeans know about tile that we don’t?
The answer is the uncoupling system the Europeans used. The uncoupling system starts with a bottom layer of mortar followed by a thin layer of sand. The tiles are then set into another layer of mortar on top of the sand. The uncoupling system allowed for the tiles to float above the floor so that when the buildings began to move, shift and settle the tiles would be unaffected. Without the uncoupling system, today’s tile floors move when the buildings move. This causes multiple problems including: loosened grout, loosened tiles and in extreme cases the tiles can move, shift and crack, especially in larger floors.
In the past, some people have had pretty good luck by first making sure that the sub-floor was thick enough. They would applying felt paper, wire lath, and a layer of mortar before installing the tile. But that was a lot of extra work, extra materials, and extra thickness of being added to the tile floor. Recently, people have started using a product called Ditra, which applies ancient European concepts using some 21st-century materials.
Before beginning any tiling project, it is important that you start with a sound floor. Adding a membrane under the tile floor will only lengthen the life of your tile floor if the floor is structurally sound. If you notice that there is too much give when you jump up and down on the floor that probably means the floor needs to be strengthened before you begin tiling. Check the frame work below the floor, whenever possible, to make sure the size and spacing of the joists are correct for floor span.
Second, before installing the tile, you will need to roll out and cut pieces of membrane for the whole floor. It’s okay to use small pieces in areas such as thresholds to make the installation easier. If you’re putting down a heat mat for a radiant floor, install it before the membrane. Snap chalklines for each course of tile before it’s installed to help guide you so that you don’t spread more thinset mortar than necessary. For an installation over a wood sub-floor, use a latex-modified thinset that bonds well to the fabric side of the membrane.
When using your trowel, you’ll need to keep the lines going in one direction so that pockets or voids don’t form which can prevent the membrane from bonding properly. Roll out the membrane into the mortar and press it flat. Once in position, use either a 75-lb linoleum roller or a wood float to press the membrane into the mortar, establishing the bond. Make sure to push out any excess thinset otherwise this may make the floor uneven.
Most importantly, you will want to plan your tile layout for best look and least waste. This is best done by selecting the room’s focal point.Remember, once the first tile goes down, there’s no turning back. So, take as much time as you need to get the layout right and always remember, when laying tile, that the first tile determines the position of every tile in the floor.