A tile installation is meant to be flat and solid, and once the thinset mortar and grout locking the tiles in place has solidified, it can last for generations as long as the proper installation methods were followed. Unfortunately, human error can lead to failure in as little as a few weeks, with tiles bulging and coming loose. Natural disasters can also lead to the same issue, which is why it’s important to do things right the first time and install with the future in mind.
Thinset mortar is the element that holds the tiles in place on the installation surface. It is a combination of cement, sand and other man-made bonding agents, usually latex and other modifiers to create a mortar that provides solidity while at the same time having some elasticity. When mixed according to manufacturer guidelines, concrete lasts lifetimes. However, adding too much water to the mixture leads to weak, faulty mortar, which in turn leads to tiles that do not fully bond with the mortar and eventually pop up and come loose due to foot traffic or general house movement. The only solution is to reapply the tiles with a proper mixture.
Whether you use concrete board or fiber board underlayment for tile, they serve the same purpose: to provide the tile with an adequate bonding surface on top of a wood subfloor. However, you cannot simply place the underlayment on top of the wooden subfloor and nail it down. The proper installation method is to first mortar the boards in place with at least a 1/4-inch notched trowel and a thinset mortar rated for use with wood. Failing to do so leads to an underlayment that moves on top of the wooden subfloor, leading to tiles that bulge and pop up from the floor due to excess movement. Replacing the entire installation and installing the underlayment correctly is the only solution.
Grout is not a bonding agent, but it fills the joints between the tiles and helps keep them from moving around due to foot traffic or general house settling and vibrations. The shock of movement is carried throughout the bed of thinset and the grout mortar as opposed to the tiles themselves. However, faulty grout mixing leads to grout that powders out of the joint, usually as a result of too much water being added during mixing. Another problem arises when someone mixes only a portion of the grout in a bag; if the grout has settled in the bag as a dry mixture, the person is mixing coloring and pigment without all the cement and other bonding agents. For best results, always follow manufacturer guidelines for mixing grout.
Lack of Expansion Joints
One of the primary reasons for tile floors to buckle and bulge is a lack of expansion joints at the perimeters of the room. The same goes for wall installations. Tile is like any other material in that it expands and contracts with the seasons and the weather. Expansion joints always need to be left at the walls, such as into the corners on wall installations or up against the wall for floor installations. These joints are covered by baseboard (in the case of wall to floor installations) or by the opposite wall meeting at the corner. When the tile installation expands during warm months and there is no space for the tile to breathe, the resulting pressure buckles the tile installation and forces tiles loose. Always leave 1/4-inch minimum around floor perimeters and 1/8-inch minimum gaps into corners where two tile surfaces meet. Floor joints may be left uncaulked since baseboard covers it, but wall installations should be caulked.