Every tile installation requires allowances for the natural expansion and contraction of tile. These take the form of movement joints, commonly called expansion joints, which help eliminate stress in the tile when changes in conditions cause this expansion and contraction. The most common cause of movement is changes in temperature, but humidity, vibration, and changes in plane can all exacerbate the problem. Some tile types are more reactive than others to these types of conditions.
To determine where to place movement joints and how many to include, always follow the guidelines in the TCNA Handbook, including detail EJ171. At a minimum, always consider movement joints for changes in plane, the perimeter of rooms and on large expanses every 20 feet throughout the field of the tile.
Temperature considerations: Is the room exposed to sunlight? Frequent changes in temperature from changing sunlight can cause greater amounts of expansion. Is this an exterior installation? The range and extremes of temperatures must be considered. Large temperature swings will require more frequent placement of expansion joints.
Installation tenting: When the tile assembly expands and there is no place for it to go, we sometimes see tenting with a complete loss of bond and cracked tile or grout. This is often a sign that more movement joints were needed. When a tile assembly tents, the timeline is typically impacted by three causes: the rate of concrete shrinkage, the shear strength of the mortar and expansive forces (usually temperature) applied to the tile. The best defense is the proper use of movement joints and use of the right polymer modified mortar based on the conditions of the job.
CUSTOM offers two products for use in expansion joints. For everyday residential applications, use PolyBlend® Ceramic Tile Caulk (Sealant). For professional results, select CUSTOM’s Commercial 100% Silicone Sealant. Both are offered in all of CUSTOM’s 40 standard grout colors for an exact color match with the rest of the grout on the project.
If you have questions about expansion joints or the placement of movement joints on a commercial project, be sure to consult with the architect and project engineers.